Speech referenced limiting: Controlling the loudness of a signal with reference to its speech loudness

A novel method of sound amplitude limiting for signals conveying speech is presented. The method uses the frequency-specific levels of the speech conveyed by the signal to generate a set of time-varying speech reference levels. It limits the level of sounds conveyed by the signal to these speech reference levels. The method is called speech referenced limiting (SRL). It provides minimal limiting of speech while providing greater control over the loudness of non-speech sounds compared to conventional (fixed threshold) limiters. It is appropriate for use in applications where speech is the primary signal of interest such as telephones, computers, amplified hearing protectors and hearing aids. Three experiments were conducted to subjectively evaluate SRL. The results show preservation of speech loudness and quality and a reduction in the loudness of louder non-speech sounds to that of speech.