Digital USB audiometer with spectral noise-shaping

Kurzfassung

A Spanish public university has developed a digital audiometer implemented on PC and PDA (personal data assistant) computers, with new features to make low-cost and simple equipment. The signals are digitally generated in order to eliminate the harmonic distortion at low levels and increase the signal-noise ratio. The research team would like to contact with companies from the electronics sector interested in manufacturing or marketing this audiometer.

Details

ADDA (Digital Applications and Developments on Acoustics) is a research group in the Department of Ingeniería Audiovisual y Comunicaciones at Escuela de Ingeniería Técnica de Telecomunicación at Universidad Politécnica de Madrid (UPM). The group is formed by professors experts on acoustics, audio and signal processing. Ultimately, their research is focused on active noise control applications and audiology (digital audiometers), supported by public subventions of Ministry of Science and Technology (PROFIT projects). The have presented many communications at national and international technical congresses, papers and patents. Recently, they have also founded a spin-off company LEQ Ingenieros, supported by UPM, in order to develop and market their products.

The audiometer consists of a software program, installed on a personal computer (PC), and electro-acoustic transducers (as specified by the standard IEC 645-1 1992: headsets and bone vibrator). The cost of the audiometer almost depends on the price of the transducers. The generation of the signals is directly made by the computer, through the digital port USB (Universal Serial Bus), and is connected to the transducer with a USB audio adapter. In order to guarantee the specifications of distortion, dynamic range and signal/noise ratio required by the standard, the software application generates all the signals with digital algorithms applying spectral noise shaping techniques on the quantification noise. This technique and the USB digital output allow obtaining “extremely clean signals“, especially in low levels, and eliminate the design of expensive hardware equipments.

The system design is simple and professional, easy to use on any PC. The test documents are generated and printed automatically or saved as “pdf