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Effect of Timbre on Detection and Speech Comprehension in Auditory Alarms

Effect of Timbre on Detection and Speech Comprehension in Auditory Alarms

Presenter Name:Andres, Elizondo Lopez

School/Affiliation:McMaster University

Co-Authors:Dr. Michael Schutz , Dr. Joseph Schlesinger


Auditory alarms play a crucial role in many of safety critical contexts, such as medical devices and navigation systems. These alarms utilize simplistic beeps lacking the temporal dynamics of naturally occurring sounds. Simplistic tones are not easily detectable unless played at high volumes, which can obstruct hearing. We explore how insights from musical instruments can be used to improve alarms by balancing detectability and comprehension. Using the acoustic structure of the triangle, we synthesized tones mimicking key properties of the instrument to assess their affect on detection and speech comprehension. We created two classes of stimuli (1) sounds inspired by musical triangles and (2) standard alarm tones. Our “triangle” sound features the twelve most prominent frequencies, amplitudes and temporal variation of the instrument. The standard tone exhibits a “flat” shape, with energy at 261, 523, 783, 1046, and 2092 Hz. Participants follow specific vocal instructions guiding them to a block on their computer screen. Two distractor voices add to the cognitive demand of the task. Participants indicate if the alarm is heard, presenting the triangle and standard tones at different signal-to-noise ratios (SNR). Despite being matched in overall energy level, participants detected the triangle at significantly higher rates relative to the standard. For speech comprehension, the standard tone had greater performance than the triangle at lower SNRs, however, performance is significantly greater for the triangle in the loudest SNR. Suggesting that triangle inspired tones are highly detectable in comparison to the alarm standard, but this greater detectability affects speech performance.

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