The way to improve a cow's milk yield is to play Simon and Garfunkel to it - and, note for note, human beings aren't much more sophisticated, writes Peter Crawley.
Beneath the unexpectedly heavy throb of Beyoncé's r&b hit, Crazy in Love, it is hard to make out what my friend is saying. He tries again, this time adding illustrative gestures.
"Where's the dancefloor?" he asks.
Oh. There isn't one.
It is a Saturday night and we are in one of Dublin's notorious superpubs, where Beyoncé's stentorian tones seem more determined to drown out our conversation than to get us moving. I go to the bar instead.
"In the case of pubs, it's a straightforward fact that if the music is too loud you can't talk," says Dr Adrian North, a senior lecturer in psychology at the University of Leicester. Generously, he furthers the syllogism. "If you can't talk, what can you do? Have a drink. If you're talking, you're not spending any money, but if you're drinking, you are."
Perhaps you've noticed it too. More likely you haven't. You walk into a clothes shop without realising why or stay there longer than you had intended. For no particular reason, in the supermarket you choose a bottle of French wine over the Chilean.
You feel so comfortable in one café that you stay to have another coffee. And in the restaurant, something other than appetite nudges you towards a costlier dessert or a particular starter. Chances are, you have been manipulated by music.
"That's very much what this line of research is about," says North, who specialises in the social psychology of music. "It's using music to prime people to behave in a certain way."
In his career, North has determined the effects of music on the atmosphere of bars and banks, on relaxation and exercise, on choosing wine (from a cellar and a supermarket), and on dairy cows, where Beethoven's Pastoral Symphony and Simon and Garfunkel's Bridge Over Troubled Water conclusively increase the milk yield. Most recently he has turned his attention to restaurant customers, and his findings are again intriguing.
Playing classical music, pop music and no music on alternate nights in a local restaurant, North and his colleagues totted up the bills and discovered that, on average, patrons splurged out at £24 a head when serenaded by Brahms, Bach and Beethoven; doled out £22 a head against the ebullient strains of Britney Spears or the dulcet tones of Chesney Hawkes, and parted with a mere £21 in the clammy grasp of silence.
Music's effect is not subliminal, North stresses.
"There's absolutely no way it works via that route," he says. "The idea that you can be manipulated into spending money if you don't want to. There's no way that if you walked into a restaurant with a £50 note in your pocket and they put on classical music, you'd suddenly order 15 bottles of champagne. It's much more a case of turning a 50/50 decision into a 51/49 decision. It's very much when you're undecided that these effects come into play." The dice aren't loaded then, but the tables have been angled.
"It makes sure that one alternative sticks its head above the others."
In North's study, wittily entitled 'The Effect of Musical Style on Restaurant Customers' Spending' and published in the current issue of Environment and Behaviour, the music itself is relatively blameless. There is nothing intrinsic to Handel's Water Music, for example, that steers you towards the veal.
"It's an absolute function of the associations people have with the musical style," says North. He writes of "contextually appropriate congruent behaviour". Classical music conjures up associations of affluence, and the appropriate behaviour is to spend more. But he recognises that the findings would be quite different in a city-centre McDonald's.
"Fast-food chains in general don't tend to push this sophisticated upmarket image," he says. "If you take a very well-known brand, then that brand has its own identity and the music is always going to interact with that."
Hitting the streets in a contextually appropriate congruent effort to observe the effects of music in commercial settings, what hits you back is how carefully considered the choices are. From supermarkets to pubs and cafés to clothing chains, the approach is increasingly sophisticated. In most cases, any interference from the humble floor worker has been systematically removed.
When the slow groove of a Daft Punk track settles around the racks of disposable fashion in Topshop, something equally laid back and contemporary slopes in to replace it. On its eighth airing that day, nobody in Topshop can identify the tune. Each week a new tape arrives from the head office in London and every outlet is obliged to play it. The same formula fits Zara, whose mix of attenuated hip-hop, pop and the occasional incongruous Spanish song are imported from the head office in La Coruña, and Miss Selfridge, which receives two tapes of female-oriented chart pop from London every month. Repeated with merciless regularity, one wonders if the staff truly love their in-store music policy. Oh yes, responds one, and points an imaginary gun to his head.
"I really think it's a form of abuse," says Vanessa Conneely, a journalist still scarred by repeated plays of Robson and Jerome while working in a clothes store.
Indeed, the deadening inevitability of hearing Britney Spears's Me Against the Music (which has you rooting, senselessly, for the music) from store to store starts to feel like water torture. But for all the potential disgruntlement, Conneely understands the effectiveness of it.
"You can definitely influence turnover with music," she considers. The current number one or anything with a prominent bass-line, for instance, tends to lure in shoppers. "Ten minutes of adrenaline" is how she describes the onslaught of Eminem and Fatman Scoop, "that will make them throw caution to the wind."
And part with their cash accordingly.
It's what music psychologists call arousal theory.
"As music gets louder or faster it makes you more aroused, more alert," says North. "You can look at things like pulse rate and you find that it goes up. And, in turn, a couple of studies have shown that that leads to supermarket shoppers shopping more quickly, restaurant customers eating their meals more quickly."
As for the centrally disseminated tapes, North sounds uncharacteristically conspiratorial for a moment.
"There's a few of them that are up to this now," he says. Starbucks, the international coffee chain, has even begun selling its own CDs along with the house brew. "That side of things - using the music as part of its more general branding - is certainly quite well-advanced. For example, there are now music-branding consultancies."
It all comes down to the "bottom line", as North puts it. "It would really be quite bizarre to spend so much money on what the place looks like and then to ignore how it sounds. If you come to this from the marketing perspective, it makes perfect sense. If you come to it from the Joe Public perspective, you might think: 'Oh my God, this is so insidious.' Somewhere in the middle is where you get a lot of antipathy towards piped music."
Pipedown, a group that vigorously campaigns for the suppression of piped music, has cornered the market in such antipathy.
"Cows, when being milked, are supposedly more productive if lulled by piped music," fumes their manifesto. "The same principle is used to stupefy us into mindlessness before parting us from our money, votes, wits," it says.
Ultimately, the use of background music is not informed by public taste. The deciding factor is that it works. Most of us, however, will hum along oblivious to its effect and unaware of a subtle relationship between notes: drifting into your ears and sliding out from your wallet.