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Express Paper

An open source 3D printed talkbox for speech intelligibility measurements

Authors: Ponteggia, Daniele

Express Paper · Paper 238 · June 2024

Abstract

The measurement of Speech Transmission Index (STI) with an acoustic input channel requires the use of a source that simulates a human speaker. The IEC 60268-16:2020 standard suggests the possibility of utilizing a simple loudspeaker driver enclosed in a small box with a recommended opening size of less than 65 mm to mimic the directional behavior of a human voice. This device, referred to as a "talkbox" by the IEC standard, is commonly employed for such purposes. However, achieving a linear response within the octave bands ranging from 125 Hz to 8 kHz, as required by the STI measurement technique from such a small loudspeaker cone driver, is non-trivial. Commercial implementations often resort to equalization to linearize the response of the device. In this paper, we present the design and implementation of a low-cost talkbox leveraging 3D printing technology and we explore a method for linearizing the response of the talkbox using pre-distortion of the STI/STIPA signal.

Details

AES Convention
156
Paper number
238
Publication date
June 6, 2024
Affiliation
Audiomatica Srl, 50136 Firenze (Italy) (See document for exact affiliation information.)
Type
Express Paper