Hearing+Lab


 * Lab Title:** Hearing Lab


 * Primary Authors:** Kevin, Ryan, Kelsey

The goal of this lab was to study our own hearing and find out about our hearing ability with respect to standard human hearing range. Our range was tested from 30Hz to 16,000Hz (standard human range 20Hz to 20,000Hz). Also, another variable in our lab was the loudness of those frequencies, ranging from 0db to -99db.
 * Abstract:**

Imagine you are sitting in your class waiting for it to end, when you hear this piercing sound. You look around the room at your classmates trying to find an explanation. Nothing. The teacher does not even hesitate in their lecture. You conclude that it was most likely just a figment of your imagination. Several minutes pass, and you hear the same noise again. This time you are sure that there was actually a noise. You turn in your seat and nudge your friend asking if they heard the noise. Your friend smiles and responds telling you that the noise is his new ringtone. It has a very high frequency so that the teacher cannot hear it go off.
 * Introduction:**

The human range of hearing is usually listed around 20Hz - 20,000Hz. As one ages, their hearing ability often worsens. Several things could damage the ears through the course of their lifetime. Such as: loud concerts, loud ear buds, construction sites, and other extremely loud noises. The repetition of these harmful activities results in the range of human hearing diminishing. While other times the cause could just be that the person is growing older and their senses are not as keen as they used to be. These are all possible reasons as to why the teacher could not hear the ringtone on the phone during class.

There were two main items needed in order to participate in this lab. The first being a computer so that one could access the website([]), and the second being a set of headphones to test your hearing. The website offered a graph (as shown below) that one could use to find their personal hearing range. They would click on a box and determine whether or not they could hear a sound, if they could they would go to the box right below it until they could no longer make out any sound.They would start in the 1 kHz column, because that would be the "reference sound", or the one that someone would compare all their other columns to. Once that point was reached for that particular column, they would move onto the next one repeating the same exercise, but also comparing each successive column to the reference sound.
 * Methods:**

Having completed the lab all on our own, this is the graph one of our members got based on the sounds he could hear. Using the 1 kHz column as the reference sound, the results that were obtained were, according to the site, very similar to what they would expect someone to get.
 * Results:**



Around 1 kHz to 4 kHz was where the hearing level was most sensitive to higher frequency sounds. The sounds heard did sound alike to the 1kHz reference sound, which is a positive sign that the lab was conducted the right way. Even though sensitivity to sounds was lower at high and low frequencies, that is common. Being young, higher frequencies are still heard quite well, even though we may not always want to hear them. These results do in no way represent the entire group's hearing levels, because of the possible existence of hearing damage in the person whose results these are (A few too many front row rock shows). By doing this at home rather than at school, certain possible elements of error were eliminated from the lab by using a pair of Sennheiser over ear headphones in place of possibly faulty iPod in ear headphones. Computer speakers often have terribly poor response, especially at low frequencies, which makes them inefficient for this lab, and iPod headphones often lack the power to completely block outside noise. The seal created between the Sennheiser headphones and the ears of the person conducting the lab made sure that the only sounds heard were the ones for this lab. This graph does show the standard loudness curve in blue, which has an almost identical shape (give or take) to the results obtained when the lab was conducted. For the most part, our results were very average, which given our age, is not surprising.

According to our data, the subject of this experiment has relatively average hearing compared to the standard human hearing range. As seen in the graph above, most humans hear a few frequencies better than others in their threshold of detection. In this case, the student's ears detected sounds from 1 kHz to 12 kHz the best and as the frequencies increased or decreased, their ability to hear the sound dropped. This obviously can vary amongst other students since everyone has a different threshold of detection. However, our subject was able to hear all of the frequencies from 30 Hz to 16,000 Hz, all of which lie in the standard range of hearing. From the shape of the graph and the fact that the subject was able to hear all of the sounds, it is safe to say that this person has relatively average hearing. Now, this can change over time as this person is exposed to possible sources of hearing damage. This test can be used, if done properly, to keep track of your hearing over time. That way, you will know if you have had hearing damage and will be able to compare your results to the standard graph.
 * Conclusion:**