Difference and summation tones are perceived at arithmetic combinations of presented frequencies

Evidence

A difference tone is perceived at the difference frequency f = f2 – f1; a summation tone at the sum frequency f = f2 + f1. Tartini tones are generally applied to compound (periodic but not sinusoidal) generators, whereas difference tones refer to simple sinusoidal generators. We need a blanket term, one that acknowledges that all these effects, in spite of their nuances, do share some common roots. We call them phantom tones. A phantom tone is a tone not in the sound presented to the listener but heard by the listener nonetheless. Are all the various phantom tones essentially the same phenomenon? — Eric J. Heller, Why You Hear What You Hear- An…, 2276

Categorization

• DEFINE: Crisp definition of difference, summation, and Tartini tones plus the unifying term ‘phantom tones’.
• QUESTION: The chapter’s driving question — whether all phantom tones share one mechanism — is worth tracking as the explanation develops.