A testament to my hard work and your good luck that you have gone all the way to the Animals unit before finding missing audio to report. Every sentence and every word must be recorded individually by volunteers. At minimum, every second sentence from the beginning up through lesson 1 of body parts does have a female voice recording, and most of the early ones also have male voice recordings.
We'll let you know when to report missing audio. In the meantime, please report audio that is crackly or has background sounds, but if you're going through the course quickly, you'll find that the presence of audio drops off quite sharply soon.
Now, I wrote the above, and it's true, but when I went to the incubator to record jentu' for you, I discovered that it already has female tracks, so Duo just hasn't pushed it out yet. I did it a few days ago. Sometimes it's immediate, but sometimes it seems to take a week or so for them to process new audio.
Was there a blue speaker? If there was, but it didn't play any audio, then this is a software bug and not an issue that the moderators or contributors of this course can do anything about. Report that here instead: https://support.duolingo.com/hc/en-us/articles/204728264-How-do-I-report-a-bug-