Authors: Francisco Irarrazabal, Mike Dickerson, Drew Gibson
The sport of pickleball has been on the rise for the last few years and the projections are estimating more growth for the coming years. With increasing popularity, pickleball courts are being built close to residences as part of common space communities. This has raised the awareness for people living close to courts due to the pickleball paddle noise, which might impact neighboring communities.
Pickleball noise is comprised of several interactions, one being the paddle impacting the ball and another being people cheering and shouting. The paddle impact noise is one of the issues the industry has faced, and some paddle manufacturers are claiming quiet noise characteristics of their paddles.
In this opportunity, we used the Crystal Instrument’s CoCo-80X to characterize the noise from several paddles for acoustic comparison. The equipment consisted of three (3) microphones mounted on an arch boom and seven specimens to be tested (including different paddles). The testing was done inside the MD Acoustics, LLC’s anechoic chamber at the facilities in Gilbert, AZ (see Figure 1, below).
Figure 1: MD Acoustics Anechoic Chamber and Experiment Setup
For each recording, the paddle was held by a player in the center of the chamber while hitting the ball periodically for 1 minute. The anechoic chamber has an arch boom designed to install up to eight (8) microphones and can rotate 360 degrees to scan the space. In this experiment, three (3) microphones were connected to the CoCo-80X dynamic signal analyzer, and the average from the three (3) signals was postprocessed using the CI Post Analyzer software. An example of the Post Analyzer interface is shown in Figure 2 below.
Figure 2: CI Post Analyzer Software Interface
The signal analyzer was set to record with a sampling frequency of 51,200 Hz, and the post-processing was made to average the spectrum over the complete sampling period. Additionally, the data processing included the use of the Hanning window to avoid any energy leak during the FFT calculation.
Each paddle's impact noise was characterized for comparison. The paddle noise consists of the noise radiated by the paddle and the ball. However, in this case, only the paddle is considered the first contribution to the overall noise. In general, the paddles, given their shape and dimensions, show a noise spectrum with a peak close to 1 kHz. The amplitude varies with more factors, such as the paddle surface material and the level of the impact force exerted. The paddles tested were from the most basic and economical options available in the market, as well as others with a higher trim and surface treatment.
The human ear is normally more sensitive to 1 kHz noise than other noise tones. The A-weight scale gives the 1 kHz band the lower-level modification since it has been probed that the human ear is able to listen to said frequency louder than lower frequencies.
Figure 3 (below) shows the frequency domain analysis for all the recordings. In general, each paddle shows some narrow-band noise (at different levels) in the 200 to 500 Hz band and then a peak around 1 kHz. Also, some paddles show additional harmonics at higher frequencies, although at lower levels. Some treated paddles also show an overall level lower than the non-treated ones. Still, the acoustic signature looks alike, with some differences in the frequency peak and a small difference in the level. Besides the amplitude difference, the treated paddles still do not reduce a large amount of the total noise radiated, although the improvement is promising.
Figure 3: Paddle Noise Spectra Comparison
From these results, we can conclude that the noise attenuation has been improved with the paddles engineered to be quiet, although there is still room for improvement. Noise propagation in outdoor environments depends on many factors, which can also be addressed for improvement. For example, the frequency peak shift to lower tones would help to reduce the impact on the human ear (because the A-weight scale attenuates lower frequency noise) and reduce the impact on the residential communities located close to pickleball courts.
MD Acoustics has spent the past 5 years working on numerous research and development projects (both industry and company-funded) on the design and development of quieter technologies. MD has spent the past 4 years evaluating the sport of pickleball and all aspects associated with the noise-producing media. Our work is made possible with the Crystal Instruments CoCo-80X signal analyzer and the resources available at our laboratory. Our mission is to ensure that our clients receive the best acoustical engineering/consulting services possible using the state-of-the-art equipment and software on the market. While there are various manufacturers of digital signal analyzers (we own many of them), we continue to heavily favor the Coco-80X as our preferred analyzer device due to its simplicity, robustness, and efficiency.