Why can i hear the fluid in my ear

This engaging book explains the concepts of pitch and frequency with easy to understand examples and fun hands on experiments Why Can t I Hear That Pitch and Frequency Exploring Sound My husband is an electronics expert and happened to pick this up to browse through it He was impressed that it was accurate even though it was simplified He did mention that there were a few places where it could have been worded differently such as instead of saying something vibrates at 600 times per seconds it would be precise to read 1000 cycles per second but overall it was good Cycles per second times per second frequency all related terms but not necessarily interchangeable I would like to see an explanation of these Then I wondered about frequencies audible to the human ear after reading a page one sidebar that says The slowest vibration human ears can hear is 20 times a second This statement begs the question What is the fastest but I could not find the answer anywhere in the book I did find on page fifteen that the range of string instruments is 40 times per second for a double bass and the highest string on a violin vibrates 440000 times per second Does that mean that is the highest frequency that can be heard by the human ear or that it s so high the human ear cannot hear it I looked up some other sources for frequency of stringed instruments and I found 4400 Hz Did the author mistake Hz for 1000 Good photos support the text and great easy to do experiments for youngsters However I don t think I would be giving my students elastic bands to try Why Can t I Hear That Pitch and Frequency Exploring Sound interesting Why Can t I Hear That Pitch and Frequency Exploring Sound