The Sound of Coffee Tells the Tale of its Molecular Structure

Jill Linz – jlinz@skidmore.edu

Skidmore College, 815 N Broadway, Saratoga Springs, NY, 12866, United States

Additional Authors
Emily Gross
Oliver Goldman
Owen Young

Popular version of 2pMU1 – Molecular Sounds
Presented at the 190th ASA Meeting
Read the abstract at https://eppro01.ativ.me/web/index.php?page=IntHtml&project=ASASPRING2026&id=4069932

–The research described in this Acoustics Lay Language Paper may not have yet been peer reviewed–

What does coffee sound like? The molecules that make up your morning cup of coffee was one of several molecules explored using a promising new sonification method for creating musical tones from molecular absorption spectra. Sonification is the process of converting scientific data to audible frequencies, which can then be turned into sound through standard audio programs. By relating the physical characteristics of the molecules to the characteristics of sound we were able to create a mapping scale that retains all the molecular information within a single grain of sound. This grain of sound was then used as the building block for the sound of coffee.

A grain is a bit of sound that exists for less time than the human ear can detect yet contains within it all the information known about the molecule. Once produced, even smaller samples of the grain were taken and used to create musically harmonic tones. The methods used to create these grains used standard methods found in quantum mechanics and in music synthesis techniques.

Figure 1. A 50 ms sound grain produced from data obtained by analyzing a coffee sample.

Figure 2a) Raw data showing the absorption spectrum of coffee.

Figure 2b) The frequency spectrum produced by the coffee sound grain shown in Fig 1. Mirror image of the spectrum is shown for comparison.

Scientists use the absorption spectrum to learn about a molecule’s atomic make-up. The shape of the peaks and curves are unique to each molecule. The peaks reveal what elements make up that molecule. Fig 2a is the absorption spectrum for a drop of coffee. Fig 2b shows a mirror image view of the frequency spectrum produced by the sound grain. The spectrum produced by our methods in Fig 2b compared to the spectrum produced by the raw data in Fig 2a validated the methods used to create the sound grain.

To create the grains, a gaussian fit method was used to determine the corresponding frequencies. These were then translated into sound using granular synthesis techniques. Granular synthesis has its origins in the Heisenberg Uncertainty Principle. Sound can exist in short bits, sometimes referred to as a quantum bit in quantum computing, or a grain in granular synthesis. These “bits” are unique waveforms in which all data is contained in a time interval of less than 60 ms, as seen in Fig 1. In granular synthesis, we were interested in stringing multiple bits very closely together to build up an interesting tone. Each tone was created by experimenting with the sample size of the sound grain and then stringing multiple wave packets together to form the sound.

Figure 3. Comparison of sample sizes used to produce the Sound of Coffee together with the resultant sound wave and frequency spectrum for small, medium and large samples.

The Sound of Coffee can be heard in the audio sample. The three tones produced follow in the order shown in Fig 3. Playing from top to bottom, small, medium and large samples are heard. While all three samples produced harmonic qualities, the frequency spectra show that the smaller the sample size became, the more harmonic the tone became.

Audio1. The sound of coffee for small, medium and large grain samples.

Our results produced a harmonic quality in coffee, as well as in other molecules, that was absent in the atom tones produced in the author’s previous work. In addition, we also noticed that the peaks were shifted slightly as we reduced the sample size. This result aligns with current research in physical chemistry. Our next step is to investigate Iodine, as it is a purer molecular form. These results may provide us more insight to the chemical makeup of molecules and how they are understood through their unique, musical sounds.