Pitch strength and annoyance of acoustic analogs of flutter echo – a pilot study



The impetus for this pilot study was the observation of flutter echoes on the aisle of a church with a barrel-vaulted ceiling. When source and receiver height were comparable, the flutter echoes consisted of a 39-msec repeating pattern of three short pulses that persisted for reverberation times of up to 5 sec. The disruptive quality of these echoes perceptually was striking. It was hypothesized that the perception of a sequence of rapidly alternating periodicity pitches might be the source of this disruptive quality. A pilot study was conducted to assess the perceived pitch, pitch strength, and annoyance of isochronous and anisochronous synthetic pulse trains involving up to three different inter-pulse intervals per pattern. Intervals of the anisochronous pulse trains were controlled to create harmonic and inharmonic relationships among the intervals, which ranged from 5-20 msec. Twelve adult college students participated in the study remotely via videoconferencing due to social distancing requirements. A modified category scaling method was used. Participants positioned a slider on a graphical user interface to reflect their ratings of pitch strength and annoyance and used a slider to adjust the frequency of a reference tone for pitch matching. Results and implications for further research will be presented.