Why do some automated phone systems use a typing sound effect?

Sometimes when I call a company's customer service phone number, an automated phone system answers. These systems will ask me questions to identify the type of information I am seeking, the type of problem I am experiencing, and/or a personal identifier (such as account number).

After I have responded to one of the system's questions, I will sometimes hear a typing sound effect played for a few seconds. It's obvious that I'm not talking to a person (sometimes the system even tells me that it's an automated system), so why play a typing sound effect?

I would think that the company would have optimized their database to be able to pull up the records (based on my account number or whatever information I provided) instantly, so they should be able to reduce the duration of the phone call if they didn't play this typing sound effect. If in fact it really does take their system some time to pull up the records, then I understand it may be helpful to give the caller some auditory feedback to let them know the call hasn't disconnected. However, it seems a typing sound effect isn't really appropriate, since no one is actually typing anything. Why not just have the automated phone system say "Please wait a few seconds while I look up your account"?