Translation:The words on the blackboard are too small!
I can hear what you're talking about, but I believe the audio is correct. It has to do with the way that some Chinese speakers say the "h" sound more forcefully than English speakers do (at least where I'm from). I believe the linguistic term for this is the that Chinese "h" is aspirated more (by some speakers, anyway). I'm not a linguist, so that might be the wrong term, but anyway, it has to do with how forceful the airflow is when the consonant is pronounced. Try listening to the recording at different volume settings. And "try" to hear it as an "h". This often helps me when I have that problem. Also note that the tone in the recording is first tone (as is appropriate for 黑 but not 可以), and that the vowel sounds are the same between those words (e i). Meaning, it's probably the way the "h" is being pronounced that's throwing you off.