Room Design Considerations for Optimal Podcasting

Madeline Didier –

Jaffe Holden, 114-A Washington Street, Norwalk, CT, 06854, United States

Twitter: @JaffeHolden
Instagram: @jaffeholden

Popular version of 1aAA2-Podcast recording room design considerations and best practices, presented at the 183rd ASA Meeting.

Podcast popularity has been on the rise, with over two million active podcasts as of 2021. There are countless options when choosing a podcast to listen to, and unacceptable audio quality will cause a listener to quickly move on to another option. Poor acoustics in the space where a podcast was recorded are noticeable even by an untrained ear, and listeners may hear differences in room acoustics without even seeing a space. Podcasters use a variety of setups to record episodes, ranging from closets to professional recording spaces. One trend is recording spaces that feel comfortable and look aesthetically pleasing, more like living rooms rather than radio stations.

Figure 1: Podcast studio with a living room aesthetic. Image courtesy of The Qube.

A high-quality podcast recording is one that does not capture sounds other than the podcaster’s voice. Unwanted sounds include noise from mechanical systems, vocal reflections, or ambient noise such as exterior traffic or people in a neighboring room. Listen to the examples below.

More ideal recording conditions:
Media courtesy of Home Cooking Podcast, Episode: Kohlrabi – Turnip for What

Less ideal recording conditions:
Media courtesy of The Birding Life Podcast, Episode 15: Roberts Bird Guide Second Edition

The first example is a higher quality recording where the voices can be clearly heard. In the second example, the podcast guest is not recording in an acoustically suitable room. The voice reflects off the wall surfaces and detracts from the overall quality and listener experience.

Every room design project comes with its own challenges and considerations related to budget, adjacent spaces, and expected quality. Each room may have different design needs, but best practice recommendations for designing a podcasting room remain the same.

Background noise: Mechanical noise should be controlled so that you cannot hear HVAC systems in a recording. Computers and audio interfaces should ideally be located remotely so that noises, such as computer fans, are not picked up on the recording.
Room shape: Square room proportions should be avoided as this can cause room modes, or buildup of sound energy in spots of the room, creating an uneven acoustic environment.
Room finishes: Carpet is ideal for flooring, and an acoustically absorptive material should be attached to the wall(s) in the same plane as the podcaster’s voice. Wall materials should be 1-2” thick. Ceiling materials should be acoustically absorptive, and window glass should be angled upward to reduce resonance within the room.
Sound isolation: Strategies for improving sound separation may include sound rated doors or standard doors with full perimeter gaskets, sound isolation ceilings, and full height wall constructions with insulation and multiple layers of gypsum wallboard.

In the example below, the podcast studio (circled) is strategically located at the back of a dedicated corridor for radio and podcasting. It is physically isolated from the main corridor, creating more acoustical separation. Absorptive ceiling tile (not shown) and 2” thick wall panels help limit vocal reflections, and background noise is controlled.

Podcast recording room within a radio and podcasting suite. Image courtesy of BWBR and RAMSA.Figure 2: Podcast recording room within a radio and podcasting suite. Image courtesy of BWBR and RAMSA.

While the challenges for any podcast room may differ, the acoustical goals remain the same. With thoughtful consideration of background noise, room shape, finishes, and sound isolation, any room can support high-quality podcast recording.

1aAA4 – Optimizing the signal to noise ratio in classrooms using passive acoustics

Peter D’Antonio –

RPG Diffusor Systems, Inc.
651 Commerce Dr
Upper Marlboro, MD 20774

Popular version of paper 1aAA4 “Optimizing the signal to noise ratio in classrooms using passive acoustics”
Presented on Monday May 23, 10:20 AM – 5:00 pm, SALON I
171st ASA Meeting, Salt Lake City

The 2012 Program of International Student Assessment (PISA) has carried out an international comparative trial of student performance in reading comprehension, calculus, and natural science. The US ranks 36th out of 64 countries testing ½ million 15 year olds, as shown in Figure 1.


Figure 1 PISA Study

What is the problem? Existing acoustical designs and products have not evolved to incorporate the current state-of-the-art and the result is schools that are failing to meet their intended goals. Learning areas are only beginning to include adjustable intensity and color lighting, shown to increase reading speeds, reduce testing errors and reduce hyperactivity; existing acoustical designs are limited to conventional absorptive-only acoustical materials, like thin fabric wrapped panels and acoustical ceiling tiles, which cannot address all of the speech intelligibility and music appreciation challenges.

What is the solution? Adopt modern products and designs for core and ancillary learning spaces which utilize binary, ternary, quaternary and other transitional hybrid surfaces, which simultaneously scatter consonant-containing high frequency early reflections and absorb mid-low frequencies to passively improve the signal to noise ratio, adopt recommendations of ANSI 12.6 to control reverberation, background noise and noise intrusion and integrate lighting that adjusts to the task at hand.

Let’s begin by considering how we hear and understand what is being said when information is being delivered via the spoken word. We often hear people say, I can hear what he or she is saying, but I cannot understand what is being said. The understanding of speech is referred to as speech intelligibility. How do we interpret speech? The ear / brain processor can fill in a substantial amount of missing information in music, but requires more detailed information for understanding speech. The speech power is delivered in the vowels (a, e, i, o, u and sometimes y) which are predominantly in the frequency range of 250Hz to 500Hz. The speech intelligibility is delivered in the consonants (b, c, d, f, g, h, j, k, l, m, n, p, q, r, s, t, v, w), which occur in the 2,000Hz to 6,000 Hz frequency range. People who suffer from noise induced hearing loss typically have a 4,000Hz notch, which causes severe degradation of speech intelligibility. I raise the question, “Why would we want to use exclusively absorption on the entire ceiling of a speech room and thin fabric wrapped panels on a significant proportion of wall areas, when these porous materials absorb these important consonant frequencies and prevents them from fusing with the direct sound making it louder and more intelligible?

Exclusive treatment of absorbing material on the ceiling of the room may excessively reduce the high-frequency consonants sound and result in the masking of high-frequency consonants by low-frequency vowel sounds, thereby reducing the signal to noise ratio (SNR).

The signal has two contributions. The direct line-of-sight sound and the early reflections arriving from the walls, ceiling, floor and people and items in the room. So the signal consists of direct sound and early reflection. Our auditory system, our ears and brain, have a unique ability called temporal fusion, which combines or fuses these two signals into one apparently louder and more intelligible signal. The goal then is to utilize these passive early reflections as efficiently as possible to increase the signal. The denominator in the SNR consists of external noise intrusion, occupant noise, HVAC noise and reverberation. These ideas are summarized in Figure 2.

Dantonio figure2

Figure 2 Signal to Noise Ratio

In Figure 3, we illustrate a concept model for an improved speech environment, whether it is a classroom, a lecture hall, a meeting/conference room, essentially any room in which information is being conveyed.

The design includes a reflective front, because the vertical and horizontal divergence of the consonants is roughly 120 degrees, so if a speaker turns away from the audience, the consonants must reflect from the front wall and ceiling overhead. The perimeter of the ceiling is absorptive to control the reverberation (noise). The center of the ceiling is diffusive to provide early reflections to increase the signal and its coverage in the room. The mid third of the walls utilize novel binary, ternary, quaternary and other transitional diffsorptive (diffusive/absorptive) panels, which scatter the information above 1 kHz (the signal) and absorb the sound below 1 kHz (the reverberation=noise). This design suggests that the current exclusive use of acoustical ceiling tile and traditional fabric wrapped panels is counterproductive in improving the SNR, speech intelligibility and coverage.

Dantonio figure3 - classrooms

Figure 3 Concept model for a classroom with a high SNR

3pID2 – The Sound of the Sacred: The State of the Art in Worship Space Acoustics

David T. Bradley –
Vassar College
124 Raymond Ave
Poughkeepsie, NY 12604-0745

Erica E. Ryherd –
Durham School of Architectural Engineering and Construction
University of Nebraska – Lincoln
203C Peter Kiewit Institute
Omaha, NE 68182-0176

Lauren Ronsse –
Columbia College Chicago
33 E. Congress Parkway, Suite 601
Chicago, IL 60605

Popular version of paper 3pID2, “The state of the art in worship space acoustics”
Presented Wednesday afternoon, May 25, 2016, 1:55 in Salon D
171st ASA Meeting, Salt Lake City

From the clanging of bells to the whisper of burning incense, sound is essential to the worship experience. It follows that the acoustic environment is paramount in the sacred place – the worship space – and thoughtful design is required to achieve a worship experience full of awe and wonder. The first intentional sacred spaces were constructed over 11,000 years ago [1] and, although architectural acoustics design practices have changed immeasurably since then, the primary use of these spaces remains essentially unchanged: to provide a gathering space for communal worship.

view from ezrat nashim - worship spaceFigure 1: Temple YoungIsrael, a 550-seat orthodox synagogue in Brookline, MA designed by Gund Partnership and Cavanaugh Tocci Associates, Inc. (Photo credit: Christopher A. Storch) ceiling dome artwork - worship spaceFigure 2: Al Farooq Masjid of Atlanta (interior view of main dome), a 1500-seat Islamic mosque designed by Lee Sound Design, Inc. and Design Arts Studio and EDT Constructors, Inc. (Photo credit: Wayne Lee)

To meet this need, the four key acoustical goals that modern worship space designers must consider are to optimize reverberation time, eliminate acoustical defects, minimize ambient noise, and maximize dynamic range. These four goals are imperative in virtually all types of worship spaces around the world, despite vast dif­ferences in religious practices and beliefs. In the recent publication, Worship Space Acous­tics: 3 Decades of Design [2], the application of these goals is seen in 67 churches, synagogues, mosques, and other worship spaces designed in the past thirty years. Each space and each religion has its own id­iosyncratic acoustic challenges, from a visually translucent but acoustically transparent partition required to separate men and women in an orthodox syna­gogue in Brookline, MA (Figure 1) to the attenuation of a focused acoustic reflection from the dome of a mosque in Atlanta, GA (Figure 2). One space featured in the book, Temple Israel (Figure 3), shows the connectedness of acoustical design in worship spaces. It is part of a special project, the Tri-Faith Initiative, a 14-acre complex in Omaha, NE uniting three Abrahamic faith groups, Temple Israel, Countryside Community Church (United Church of Christ), and The American Muslim Institute. As each of these three worship spaces is constructed on the site, they all must have the four key acoustical goals considered.

figure_3 - worship spaceFigure 3: Temple Israel, a 900-seat reform synagogue in Omaha, NE designed by Acentech Incorporated and Finegold Alexander + Associates. (Photo credit: Finegold Alexander + Associates) view from the stageFigure 4: The Star Performing Arts Centre, a 5000-seat multi-use space in Singapore designed by Arup (completed as Artec) and Andrew Bromberg of Aedas.

In the past three decades, worship spaces have seen an increased need for multi-functionality, often hosting religious services with varying acoustical needs. For example, the Star Performing Arts Centre (Figure 4) in Singapore serves as the home of the New Creation Church, seats 5000 people, and supports programing ranging from traditional worship services to pop music concerts to televised national events. Some spaces must even serve more than one religion, such as the Sacred Space (Figure 5), a multi-faith house of worship constructed in the shell of an old Boston chapel that caught fire in the mid-90s, now used for meditation, private worship, and small gatherings. These varying usage requirements require careful consideration of the acoustic design, often relying on variable acoustics such as retractable sound absorption and the use of sophisticated electroacoustics systems.

interior view - worship spaceFigure 5: The Sacred Space, 150-seat multifaith house of worship in Boston, MA designed by Acentech Incorporated and Office dA. figure_6 - worship spaceFigure 6: Mean reverberation times at 500 Hz octave band center frequency for 67 worship spaces of varying seating capacity.

Although the use of each space may vary, the most important acoustic goal remains to optimize the reverberation time. This is the time necessary for sound in a space to decay to one-millionth of its original intensity. Essentially, it describes how the sound energy decays, perceived as the fading away of sound over time. Typically, reverberation time decreases as more sound absorption is added, and increases as the size of the space increases. Figure 6 shows the mean reverberation times (500 Hz) for the various seating capacities of the 67 worship spaces. Seating capacity is generally directly proportional to size of the space, and the reverberation times here show the general trend of increasing with increasing size up to about 2000 seats. For 2000 seats and beyond, the data show a marked decrease in reverberation time. For these larger spaces, there tends to be a higher proportion of sound absorbing material used in the design, typically to allow for the use of electroacoustics systems that require a large number of loudspeakers. Spaces that rely heavily on electroacoustics to achieve the desired sonic environment require non-reflective surfaces and lower reverberation times for the microphone-loudspeaker systems to work properly.

Regardless of reverberation time, the goal remains the same, to create a gathering space for worship where the sound is sacred.

  1. K. Schmidt, “Göbekli Tepe, Southeastern Turkey: A Preliminary Report on the 1995-1999 Excavations,” Paléorient, 26(1), 45-54, 2000.
  2. D. T. Bradley, E. E. Ryherd, and L. Ronsse (Eds.), Worship Spaces Acoustics: 3 Decades of Design, (New York, NY, Springer, 2016).

4aAA5 – Conversion of an acoustically dead opera hall in a live one

Wolfgang Ahnert1, Tobias Behrens1 ( and Radu Pana2 (

1 ADA Acoustics & Media Consultants GmbH, Arkonastr. 45-49, D-13189 Berlin / Germany
2 University of Architecture and Urbanism “Ion Mincu”, Str. Academiei 18-20, RO-010014 Bucuresti / Romania

Popular version of paper 4aAA5, “The National Opera in Bucharest – Update of the room-acoustical properties”
Presented Thursday morning, November 5, 2015, 10:35 AM, Grand ballroom 3
170th ASA Meeting, Jacksonville

The acoustics of an opera hall has changed dramatically within the last 100 years. Until the end of the 19th century, mostly horseshoe-shaped halls were built with acoustically high-absorbing wall and even floor areas. Likewise, the often used boxes had fully absorbing claddings. That way the reverberation in these venues was made low and the hall was perceived as acoustically dry, e.g. the opera hall in Milan. 100 years later, the trend shows opera halls with more live and higher reverberation, preferred now for music reproduction, e.g. Semper Opera in Dresden.

This desire to enhance the acoustic liveliness in the Opera House in Bucharest led to renovation work in 2013-2014. The Opera House was built in 1952-1953 for around 2200 spectators and it followed a so-called style of “socialist realism”. This type of architecture was popular at the time, when communism was new to Romania, and the building has therefore a neoclassical design. The house was looking inside the hall like a theatre of the late 19th century. The conditions in the orchestra pit for the musicians, as far as mutual hearing is concerned, were bad as well. So, construction works took place in order to improve room acoustical properties for musicians and audience.

Ahnert-Fig.1 - opera hall

Fig. 1: Opera hall after reconstruction

The acoustic task was to enhance the room acoustic properties significantly by substituting absorptive faces (as carpet, fabric wall linings, etc.) by reflective materials:

  1. Carpet on all floor areas, upholstered back- and undersides of chairs
  2. Textile wall linings at walls/ceilings in boxes, upholstered hand rails
  3. Textile wall linings at balustrades, upholstered hand rails in the galleries

All the absorbing wall and ceiling parts were substituted by reflecting wood panels, the carpet was removed and a parquet floor was introduced. As a result, the sound does not fade out anymore as in an open-air theatre but spaciousness may be perceived now.

The primary and secondary structures of the orchestra pit were changed as well in order to improve mutual hearing in the pit and between stage and pit.  The orchestra pit had the following acoustically disadvantageous properties:

  • Insufficient ratio between open and covered area (depth of opening 3.5 m, depth of cover 4.7 m)
  • The height within the pit in the covered area was very small.
  • The space in the covered area of the pit was highly overdamped by too much absorber.

Ahnert_Fig.2 - opera hall

Fig. 2: new orchestra pit, section

The following changes have been applied:

  • The ratio between open area and covered area is now better by shifting the front edge of the stage floor to the back: Depth of opening is now 5.1 m, depth of cover only 3.1 m.
  • The height within the pit in the covered area is increased by lowering the new movable podium.
  • The walls and soffit in the pit are now generally reflective, broadband absorbers can be placed variably at the back wall in the pit.

After an elaborate investigation by measurements and simulation on site a prolongation of the reverberation time of 0.2-0.3 s was reached to actual values of about 1.3 to 1.4 s.

Together with alterations of the geometric situation of pit, the acoustic properties of the hall are now very satisfactory for musicians, singers and the audience.

Beside the reverberation time, other room acoustical measures such as C80, Support, Strength, etc. have been improved significantly.

5aMU1 – Understanding timbral effects of multi-resonator/generator systems of wind instruments in the context of western and non-western music

Popular version of poster 5aMU1
Presented Friday morning, May 22, 2015, 8:35 AM – 8:55 AM, Kings 4
169th ASA Meeting, Pittsburgh

In this paper the relationship between musical instruments and the rooms they are performed in was investigated. A musical instrument is typically characterized as a system that consists of a tone generator combined with a resonator. A saxophone for example has a reed as a tone generator and a comical shaped resonator that can be effectively changed in length with keys to produce different musical notes. Often neglected is the fact that there is a second resonator for all wind instruments coupled to the tone generator – the vocal cavity. We use our vocal cavity everyday when we speak to form characteristic formants, local enhancements in frequency to shape vowels. This is achieved by varying the diameter of the vocal tract at specific local positions along its axis. In contrast to the resonator of a wind instrument, the vocal tract is fixed its length by the dimensions between the vocal chords and the lips. Consequently, the vocal tract cannot be used to change the fundamental frequency over a larger melodic range. For out voice, the change in frequency is controlled via the tension of the vocal chords. The musical instrument’s instrument resonator however is not an adequate device to control the timbre (harmonic spectrum) of an instrument because it can only be varied in length but not in width. Therefore, the players adjustment of the vocal tract is necessary to control the timbre if the instrument. While some instruments posses additional mechanisms to control timbre, e.g., via the embouchure to control the tone generator directly using the lip muscles, for others like the recorder changes in the wind supply provided by the lungs and the changes of the vocal tract. The role of the vocal tract has not been addressed systematically in literature and learning guides for two obvious reasons. Firstly, there is no known systematic approach of how to quantify internal body movements to shape the vocal tract. Each performer has to figure out the best vocal tract configurations in an intuitive manner. For the resonator system, the changes are described through the musical notes, and in cases where multiple ways exist to produce the same note, additional signs exist to demonstrate how to finger this note (e.g., by providing a specific key combination). Secondly, in western classic music culture the vocal tract adjustments predominantly have a correctional function to balance out the harmonic spectrum to make the instrument sound as even as possible across the register.


PVC-Didgeridoo adapter for soprano saxophone

In non-western cultures, the role of the oral cavity can be much more important to convey musical meaning. The didgeridoo, for example, has a fixed resonator with no keyholes and consequently it can only produce a single pitched drone. The musical parameter space is then defined by modulating the overtone spectrum above the tone by changing the vocal tract dimensions and creating vocal sounds on top of the buzzing lips on the didgeridoo edge. Mouthpieces of Western brass instruments have a cup behind the rim with a very narrow opening to the resonator, the throat. The didgeridoo does not have a cup, and the rim is the edge of the resonator with a ring of bee wax. While the narrow throat of western mouthpiece mutes additional sounds produced with the voice, didgeridoos are very open from end to end and carry the voice much better.

The room, a musical instrument is performed in acts as a third resonator, which also affect the timbre of the instrument. In our case, the room was simulated using a computer model with early reflections and late reverberation.

Braasch 1 - wind instruments

Tone generators for soprano saxophone from left to right: Chinese Bawu, soprano saxophone, Bassoon reed, cornetto.

In general, it is difficult to assess the effect of a mouthpiece and resonator individually, because both vary across instruments. The trumpet for example has a narrow cylindrical bore with a brass mouthpiece, the saxophone has a wide conical bore with reed-based mouthpiece. To mitigate this effect, several tone generators were adapted for a soprano saxophone, including a brass mouthpiece from a cornetto, a bassoon mouthpiece and a didgeridoo adapter made from a 140 cm folded PCV pipe that can be attached to the saxophone as well. It turns out that the exchange of tone generators change the timbre of the saxophone significantly. The cornetto mouthpiece gives the instrument a much mellower tone. Similar to the baroque cornetto, the instruments sounds better in a bright room with lot of high frequencies, while the saxophone is at home at a 19th-century concert hall with a steeper roll off at high frequencies.

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