Ruth Mortimer pointed out a great example of how sound matters for brands in her article Branding the Perfect Pitch in Brand Strategy (February 2005).

In Las Vegas it is not music that greets you when you enter a casino, it is the sound of coins coming out of slot machines. A few years ago the slot machines were changed so that the winner did not get a pocket full of coins but a piece of paper that stated the amount of money he was entitled to. This completely changed  the sound of the casino from money pouring out to printing noises. The casinos soon found out that this was not a good change. The solution was simple, now the machines produce the sound of coins when ever someone wins.

citizensound says:

Just like the casinos, many companies learn the hard way of the importance of sound to both consumer experience and revenues. A little bit of insight on how sound plays a critical role to driving the footfall of the casino would have minimised revenue losses for them.

Thanks to Signy Leifdottir for finding this one…