How We Tested Sound Monitors

By:
RJ Spurrier
Review Editor
BabyGearLab

Last Updated:
Thursday
June 1, 2017

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As we do in all our reviews, we started by researching the top-rated and most popular baby monitors to see which should be included in our hands-on testing. We considered potential options with different features in a variety of price ranges. In total, we looked in detail at over 40 baby monitors ranging in price from $16 to $300, before narrowing down the list to 9 finalists that we put through our entire series of tests.

Baby Monitor Torture Testing


We put each baby monitor through a myriad of tests to see which performed the best. These tests are designed to stress each monitor's capabilities objectively for range, sound quality, ease-of-use, features, battery life, and more. We used a combination of lab tests and real-world use to influence our ratings and opinions.

To create a controlled environment, we recorded the sound of a baby crying and background white noise from an actual nursery and created an MP3 loop that we played on an iPod. This allowed us to test each monitor under identical conditions. We used an industrial sound monitor to measure sound volumes and a commercial-grade distance meter to measure open-field and indoor range tests for accuracy.

Sound Clarity Testing


It's not critical that you get crystal clear sound capability from your baby monitor, after all, you aren't listening to your favorite album you just want to know if baby needs you. As long as you can hear a baby cry, your monitor is functional, but it's certainly nice to have clear, distortion and static free sound. In practice, a monitor's sound fidelity is typically degraded by static or background hiss (like a radio tuned between stations) this inhibits your ability to hear baby clearly and may limit your ability to get much-needed sleep. The sound clarity and quality vary widely between monitors. We tested each monitor for both sound fidelity (does the monitor clearly reproduce the sounds in the nursery) as well as hiss and static.

Interference Testing


Baby monitors suffer from two primary types of signal interference. One is the degradation of sound quality as the distance and number of walls is increased. This is particularly noticeable on analog monitors or the lower-cost options where the interference can reach intolerable levels with moderate indoor obstruction (>50 ft and 4 walls). This is part of the reason we only chose digital monitors for testing this time around. The other common source of interference is from other radio frequency devices such as other baby monitors (perhaps a neighbor's monitor) and wireless telephones. The higher end and digital technology monitors seem impervious to this kind of interference in our tests, automatically finding a clear channel for communication.

Sound Level & Sound Activation


We used a professional-grade Extech sound monitor as part of our sound volume and clarity testing process.
We used a professional-grade Extech sound monitor as part of our sound volume and clarity testing process.
We used a looping MP3 track that cycled between 30 seconds of a baby crying and 30 seconds of background white noise. We placed the baby nursery unit of each monitor in one room, and 4 feet in front of it, we played that track at a standard volume setting. In the room next door we used a sound meter to measure the max and min sound db volume levels from the parent unit. Each parent unit was turned to maximum volume for this test, and we recorded the sound level 5 inches from the monitor (that db value is displayed in the Max Sound row of our comparison table). For those monitors which had a Sound Activation feature, we wanted to ensure that they would activate when the baby cried, but could still filter out the background noise. If they did filter out the background noise, you'll see in our comparison table the min sound of 0 db (meaning that background noise was completely filtered out). If Min Sound is not 0 db, then you'll see what the background white noise sound level was (when the monitor was set at max volume).

Ease-of-use Testing


We measured the time to setup each monitor and rated the ease of operating it. We tested the control features such as turning on/off, adjusting sound activation sensitivity (if that feature was provided), talk-to-baby, linking/pairing of units, etc. For the most part, the sound-only monitors are easy to setup and use.

We also considered how the various available features influenced the user experience, and whether or not they improved the overall experience or made the monitor more frustrating to use. Being simple isn't necessarily an asset for ease of use, being able to use the product and benefit from its features is what makes one product easier to use over another.

Range Testing


Some of the most important tests in our point of view are those that measure range. It is critical that your baby monitor operates in your home between the baby's room and your master bedroom. Ideally, your monitor will also work properly between baby's room and other rooms as well, but given the primary, at night use the master bedroom is non-negotiable. Most monitors have some range specification listed on the box. However, we found these ranges to be unreliable at predicting actual performance, and wildly out of sync in some cases with our real world experience.

Indoor Range Test


We used a professional grade distance meter  the Kesson Road Runner  to make our range measurements
We used a professional grade distance meter, the Kesson Road Runner, to make our range measurements
Indoor performance is the shizzle when it comes to baby monitors. While open field range tests are fun to look at, they don't mean jack (unless of course, you plan to leave the baby alone in an open field, which we don't recommend). What truly matters is how the baby monitor performs inside your house, and that means dealing with walls, interference from other wireless devices in your home, and the potential interference from monitors and phones in your neighbor's homes. To test indoor range, we obtained access to a home that had a unique straight-line torture-test situation where we could test each baby monitor's ability to pass through up to 8 indoor walls over a 125' long distance. This home had active wifi networks, wireless phones, multiple cell phones, and various other wireless gadgetry providing an ideal environment to separate the weak from the signal strong monitors. We recorded the distance and number of walls each monitor was able to effectively transmit through. In some cases, that distance was limited by the monitor's ability to maintain a signal connection, and in other cases, it was due to the level of interference to reaching an unacceptable level.

Open Field Range Test


Most manufacturers provide a specification for the range in feet or meters that are an open-field (unobstructed range) distance. We wanted to see whether we could duplicate their claimed measurements in our tests. To do so, we used our baby-crying MP3 loop to play into each monitor's nursery unit and then walked the parent unit away until it either lost the signal, or the interference became unacceptable.

Some products managed to exceed the claims on their boxes, while others struggled to even come close to the claims. As a result, those claims get our "pants on fire" rating for credibility.

Battery Life Testing


We tested battery life for each monitor after fully charging the parent unit (or with fresh batteries) and in operation with its matching nursery unit. Battery life was measured in hours and rounded to the nearest 10th of an hour (6-minute interval).

Note that in our experience battery life degrades over time, and we'd expect all the monitors to need replacement rechargeable batteries within a year or so of regular use.

EMF


EMF values were recorded using an EMF reader at approximately 6 inches, 3 feet, and 6 feet away from the parent and baby device. All the monitors were tested in the same location with same ambient EMF recording to eliminate erroneous readings related to external products other than the monitors. Values were recorded by circling the units and taking an average of the measurements at various points in the circle. The tests were repeated multiple times and in different locations to ensure the accuracy of the average readings.

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