  Auditory feedback plays an essential role in the regulation of the
fundamental frequency of voiced sounds. The fundamental frequency also responds
to auditory stimulation other than the speaker's voice. We propose to use this
response of the fundamental frequency of sustained vowels to
frequency-modulated test signals for investigating involuntary control of voice
pitch. This involuntary response is difficult to identify and isolate by the
conventional paradigm, which uses step-shaped pitch perturbation. We recently
developed a versatile measurement method using a mixture of orthogonal
sequences made from a set of extended time-stretched pulses (TSP). In this
article, we extended our approach and designed a set of test signals using the
mixture to modulate the fundamental frequency of artificial signals. For
testing the response, the experimenter presents the modulated signal aurally
while the subject is voicing sustained vowels. We developed a tool for
conducting this test quickly and interactively. We make the tool available as
an open-source and also provide executable GUI-based applications. Preliminary
tests revealed that the proposed method consistently provides compensatory
responses with about 100 ms latency, representing involuntary control. Finally,
we discuss future applications of the proposed method for objective and
non-invasive auditory response measurements.

Sound;Audio and Speech Processing;Signal Processing