Forty years of research. One pilot. The evidence we have so far.

Milliman (1982) found shoppers walked more slowly under slow-tempo music and daily sales rose. Knoferle et al. (2011) refined the finding. Tempo on its own did not move sales. The lift came when tempo and other musical choices fit together. Most retail music vendors have the thermostat. They do not have the room.

Areni and Kim (1993) found classical music in a wine store led customers to choose more expensive bottles, not more bottles. North et al. (1999) found shoppers chose French wine over German roughly three-to-one when French music played. When music matches how the customer reads herself, willingness to pay rises (North, Sheridan & Areni, 2016).

Yalch and Spangenberg (2000) tested familiar and unfamiliar music in a department store. Shoppers exposed to familiar music left 8 percent sooner. They enjoyed it more. They left faster. Original music is unfamiliar by definition. That is why it works.

Jacob, Guéguen and colleagues (2009) played romantic music in a flower shop and measured a 28.6 percent increase in spending. The inverse holds too: when the music does not fit the shopper, that lift is forfeited. North, Shilcock and Hargreaves (2003) found prestige-fit music lifted spend per head, while music that did not fit landed level with no music at all. Getting it wrong costs you money.