Preferred Name
Ben Stone
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.
ORCID
https://orcid.org/0009-0006-3144-292X
Date of Graduation
12-16-2023
Semester of Graduation
Fall
Degree Name
Master of Science (MS)
Department
Department of Graduate Psychology
Second Advisor
Lincoln Gray
Third Advisor
Jeff Andre
Abstract
Individuals are capable of discerning high- and low-quality digital audio, but the current evidence tends to confound sampling rate and bit depth (see Mizumachi et al., 2014). When bit-depth is constant, higher sampling rates can be discerned (Oohashi et al., 2000). It likewise has been argued that 16- and 24-bit audio can be distinguished when sampling rate is constant (Kanetada et al., 2013). The present study aimed to evaluate bit-depth-related perceptual ability using simplified tone stimuli in order to determine at which point from 8- to 24-bit that further increases in bit-depth resolution are no longer perceptually beneficial. Potential contributions of fundamental frequency and timbre (i.e., spectral and amplitude envelopes), were evaluated through use of synthesized sawtooth waves and sampled clarinet, piano, and violin tones that were systematically impoverished in bit-depth resolution and presented in a 4I2AFC task. Natural instrument tones were more discernable than synthesized tones, particularly when the tones were more dynamically variable and when significant portions of the tone were low in amplitude (e.g., piano and clarinet samples). This indicates that low amplitude may make bit-depth differences more apparent due to the differential impact of equivalent linear amplitude changes, depending on the starting amplitude, on the perceptual manifestation on a log scale. However, regardless of timbre or fundamental frequency, participants could not detect differences between 24-bit tones and any tone at or above 14-bit resolution. Although bit-depth resolutions beyond the CD standard of 16-bit provide benefits of lower noise-floor and greater dynamic range, it cannot be said that there are clear perceptual benefits with respect to consumer music playback or psychoacoustic testing which utilizes brief stimuli, as was the case in the current study. To further evaluate the benefits of higher bit-depth resolutions, research utilizing stimuli that are dynamically variable and/or generally low in amplitude ought to be conducted.
