These pages contain a number of audio clips illustrating the uses of non-lexical utterances in casual English dialog.
The data and a model are described in Non-Lexical Conversational Sounds in American English, an article in Pragmatics and Cognition (2006).
In the diagrams, each strip includes two tracks and a timeline. In each strip the top track is one speaker and the bottom track the other. Each track includes: a transcription, the signal, the pitch in red, and the 26th percentile pitch level (horizontal blue dotted line).
The Backchannel Facts page.
The Ideophone discussion on Is Huh a Universal Word?
A lecture on Clicking and Tutting: esxtraordinary sounds in everyday talk, by Richard Ogden
The Paralanguage page at ESL Lab, with 10 sound clips (ssh, hehehe, whee, tsk, uh-oh, ouch, etc.)
The Switchboard Transcription FAQ at Mississippi State, with more examples of grunts found in conversation.
Melissa Wright's page of Clicks as Markers of New Sequences in English Conversation.
The ICSI Switchboard Transcription Project, with papers and links about related issues.
The Responsive Systems Project page, which describes why such utterances are of practical importance.
Margaret Magnus' Bibliography of Phonosemantics.