I have a couple of tapes that I'd like to record to my Mac. I thought it was a simple matter of connecting the "phones" socket on the cassette player (an aged Aiwa walkman) to the headphone socket on the Mac, using a sound jack. But this isn't working. The tape is playing, If I connect the cassette player to a speaker with the jack, I can hear the sound. But when I connect it to the Mac, I can't.

In the System Preferences, the only input showing is Internal Microphone. Is there any way to add the sound jack as another input?

I assume that if I can get the computer (MacBook Air, Yosemite) to play the tape I can then use something like Audio Hijack to record it.