Does the slapstick really sound like the crack of a whip?
Daniel Ludwigsen – dludwigs@kettering.edu
Kettering University, Flint, MI, 48504, United States
Jordan Maxgay
Popular version of 2pMU11 – Acoustic characteristics of the slapstick
Presented at the 190th ASA Meeting
Read the abstract at https://eppro01.ativ.me/web/planner.php?id=ASASPRING2026
–The research described in this Acoustics Lay Language Paper may not have yet been peer reviewed–
The crack of the whip has been a well-loved sound effect in holiday pops concerts since the mid-twentieth century, when “Sleigh Ride” by Leroy Anderson debuted. The effect is created by a percussionist slapping two wood sticks together, but not all slapsticks, or “orchestral whips,” sound the same. This study compared five widely available commercial versions of the percussion instrument, explored the dynamic control available to the percussionist, and measured the directivity of the sound radiated from the instrument. We found that design details and, to a lesser extent, playing intensity affect the character of the sound. The best slapstick is a question of opinion, but some slapsticks mimic the real crack of a whip more closely than others.
In our study, five different instruments were played five times each, at a moderate volume in an anechoic environment fitted with absorbing wedges to minimize room effects. The average spectrum of these five strikes shows their amplitudes across the range of human hearing. The spectra shown in Figure 1 illustrate the sound of these instruments. As a group, the general spectral characteristics include a high-frequency rolloff, a broad peak between 1000 and 3000 Hz, and varying degrees of low-frequency rolloff.
The two smallest of the five utilize a spring hinge for one-handed operation. They stood out among the group in the high-frequency range (above 2000 Hz), but were weaker in low frequencies. The longest model, the “Sleighride Special,” and an instrument from Ron Vaughn with unique blind-hole features on the contact faces, provided the best low-frequency response. The Ron Vaughn model has a notably warmer tone. All five slapsticks are included in length order in “SlapsticksLarge2Small.wav”: (a) Sleighride Special, (b) Pearl PSS100, (c) Ron Vaughn, (d) Timber Drum Co., and (e) Liberty 16.
Using frame-by-frame video analysis to estimate the speed of the wood slats as they come together, we clearly distinguish the two-handed (5 to 9 radians per second) and one-handed instruments (20+ rad/s).
Figure 1. Averaged spectra of the five slapsticks, shown on a logarithmic frequency axis that reflects human hearing. The dashed line curves represent the two one-handed slapsticks, while the two-handed versions have solid line spectra.
Figure 1. Averaged spectra of the five slapsticks, shown on a logarithmic frequency axis that reflects human hearing. The dashed line curves represent the two one-handed slapsticks, while the two-handed versions have solid line spectra.The dynamic level, which corresponds to how hard the slats are brought together, has a slight effect on the instrument’s tone. Playing the Pearl slapstick at a forte dynamic level, the average angular speed was 26 rad/s, and the spectrum tapered off by about -7 dB/octave at frequencies above 2000 Hz. We tested four successively quieter dynamic levels, down to pianissimo, as shown in Figure 2. The overall levels decreased as expected, but the high frequency rolloff increased to roughly -14 dB/octave. This changes not just volume but also timbre, increasing the brightness of the tone for louder cracks.
Finally, we made preliminary measurements of the directivity of the sound radiated by the Pearl slapstick. Four microphones were placed in one quadrant of a circle around the instrument, both in the horizontal and vertical planes, at 0°, 30°, 60°, and 90°. A more complete study is needed, but our preliminary results indicate that, regardless of frequency, sound is roughly the same in any direction.
Figure 2. Averaged spectra from the Pearl slapstick at five different dynamic levels, loud (forte) to very soft (pianissimo). The overall spectra have lower levels with quieter playing, and a similar shape in the low-frequency range. Above 2000 Hz, louder sounds contain proportionally more high-frequency content, giving a brighter tone.