puretone

Puretone refers to a sound that contains a single frequency, ideally represented by a sine wave with minimal or no harmonic content. In theoretical acoustics, a pure tone is the simplest possible sound; real-world sounds are often more complex and contain multiple frequencies and noise. In psychoacoustics and hearing science, pure tones are used as controlled stimuli to study perceptual attributes such as pitch, loudness, and masking.

In audiology, pure-tone audiometry is a standard procedure for assessing hearing sensitivity. The test presents pure tones at a set of standard frequencies, typically ranging from 250 Hz to 8000 Hz, to determine the quietest sound a person can hear at each frequency. Stimuli are delivered via headphones or insert earphones, and sometimes via bone conduction to evaluate the inner ear independently of the outer and middle ear. The subject indicates when they hear a tone, and the results are plotted on an audiogram, usually expressed in decibels hearing level (dB HL). Audiograms help diagnose types of hearing loss and guide treatment decisions, including hearing aids or medical referral.

Generation and measurement of pure tones are achieved with sine-wave oscillators in both clinical instruments and research setups. Calibration ensures that the output matches specified sound pressure levels or hearing-level references. In research contexts, pure tones are employed to investigate auditory processing, such as pitch discrimination and temporal resolution, as well as to study tonal masking effects.

Limitations include the fact that most natural sounds are not pure tones, and the ear’s response varies with frequency, amplitude, and context. Pure tones thus serve as a precise, simplified tool for controlled auditory testing and experimentation.