First of all, thank you for helping us by gathering sound and heart rate data in New York during the 2022 study trip! Your data significantly improves our understanding of the impact of sound health.

Data Collection Results

The following shows some insights into the data you have collected. If you have any questions or would like your own copy of your data, feel free to write me on .

Definitions

You collected data using:

– A commercially available hearing aid (Oticon Opn S)

– A commercially available wearable (Garmin vivosmart 4)

– An iPhone with iOS 14 or higher

Every 20 seconds, the hearing aid sends estimates of the sound environment to the iPhone via Bluetooth while the wearable sends information about the instantaneous heart rate (also via Bluetooth) at each detected heart beat. Your sound-locked heart rate is then estimated as the mean heart rate from -5 seconds to +5 seconds centered on each sample of the sound environment.
The sound environment is divided up in two dimensions: Loudness and Clarity.
Loudness is also known as sound pressure level (SPL) and represents the pressure of the sound wave on your ear-drum. SPL is usually measured in decibel (dB), which is a number that indicates how much more pressure you experience from the basic air pressure during quiet (SPL = 0 dB). In addition, as the sound wave consists of signals in many different frequencies, the SPL is usually an average across all frequencies we can hear (20 to 20000 Hz). In this analysis, we use “a-weighted SPL” (dBA), which just means that the averaging across frequencies is weighted by a function resembling what the human auditory system does.

Clarity is the difference in loudness (in dBA) between background noise and sound sources - for example a speaker you are trying to listen to. The hearing aid constantly measures the background noise loudness level by classifying if an incoming sound is noise or not (based on machine learning). We can then subtract this noise level from the overall loudness level and derive a value representing the signal-to-noise ratio - that is, how much louder is the interesting sound signal (e.g., speech) compared to the noise.

Lastly, sound-induced “stress” is defined as the change in heart rate cased by an extrinsic factor related to the sound environment. For example, an increase in Loudness is usually followed by a stress reaction represented by an increase in heart rate. Thus, stress can take on positive values (i.e. a stress reaction) or negative values (i.e. a relaxing reaction) depending on the sound you are exposed to (and what you are doing).

Amount of data collected

We can therefore simply count the number of data logs to learn how many hours of data gathering (i.e. logging) you have performed. The figure below shows how this is distributed over the days during the trip with colors to indicate which Team the data came from. Note, the heart rate data is normalized so that the numbers indicate a %-change from your individual mean heart rate across the whole trip.

On average, you collected more than 16 hours of data per hour across the four days. If all of you had full connectivity this number would have been 24. But considering the “real world” nature of the data collection it is still impressive that close to 70% of the maximum available data were collected across four full days!

Noise accumulation and stress

Next, we look at the noise dose you accumulated each day of the trip. Being in loud sound environments for longer periods of time increase the total noise dose you are exposed to. The noise dose is calculated as the accumulated noise in relation to a 8 hour working day. This means that 100% is the recommended maximum to avoid occupational health effects from noise. For example, the limit of 100% is reached in 4 hours if you are exposed to 88 dBA noise and in only 1 hour if the noise is constant 94 dBA.

The average noise accumulation represents the joint exposure across all Audio Explorers. Shared events (for example our dinners) therefore contributes more to the accumulation than individual noisy events (some of you might have been in more noisy environments during free time than others). Nevertheless, the noise dose and the stress levels (color from green to red) represent expected levels when visiting New York and participating in the Audio Explorers study trip!
We can also look at the contribution to the shared noise dose from each team individually. This is shown in the bottom plot. When the accumulation seems to drop, this indicate that one or more team members stopped gathering data (maybe due to connectivity issues).

Evidently, the most noisy and stressing day was on Day 3. This makes sense since this was the day we went to the amusement park at Coney Island and enjoyed a Drag Queen show starting around 18:00.

Maps

We can also inspect how the sounds you experienced in New York were located (and also track where you went). Zoom in and see what sound you logged where you went. Note: to reduce the amount of GPS noise each dot represents the mean (lon, lat) coordinate across 1 minute corresponding to 3 GPS samples.

Sound Loudness, Sound Clarity, Stress, and trip information

Check the box for which data you would like to see.

Time-series

Sound and stress fluctuates throughout the day with the activities we perform. It is therefore interesting to inspect the time-series of these data to reflect back on particular events and their impact on sound-induced stress. The below plot shows your data across time. Each color is one person and each dot represents a mean value across 20 minutes.

Draq Queen Show

Evidently, the period during the drag show is the loudest while the Coney Island visit is a bit more stressing. In fact, lets zoom in on the show and plot the average loudness, clarity, and stress across each team.

To get more insights into how stress and sound exposure can change over time, we zoom in on the data collected during the Drag Queen Show on day 3.

Most noticeably, stress increase steadily across the event for all teams (except “Hearing Oats” and to some extend “The Vikings”) indicating you become more engaged - and maybe also more physically active! The four most stressed teams (“Gruppe 6”, “Pole Zero Heros”, “Von Mises”, and “The Fellowship”) also experience the loudest noise during the event!

Overall noise exposure and induced stress for each Audio Explorer

Finally, we can estimate the degree to which each of you experienced increased heart rate (stress) and excessive noise during the joint activities across the 4 days. Here, noise is defined by both the loudness and the noise level (a combination of SPL and SNR). Each point in the plot represents one of you and the colors indicate the event.