Analysis: the science of being a left hand phone person or a right hand phone person

By Harun Siljak, TCD

I don’t know about you, but I carry the house keys in my left pocket (being left-handed) so the phone ends up in my right pocket. So, when I answer it, it will be my right ear doing the job. How does this affect my health and the quality of the call?

The mobile phone has been around for a while now. We’re preparing for the fifth generation of wireless mobile communications  and half of the Irish population can’t remember the days before people started walking around with phones pressed to their ear. With a technology so pervasive come the inevitable concerns: do people pay attention to the road while on the phone? Are phones an addiction? Do they cause cancer? How can I get a good signal?

While such concerns are continuously investigated by the experts, rumours travel faster than scientific publications. That is how we end up reading online advice urging us to use your left ear when making a call. If you don’t, according to the image circulating on social media, the radiation will "affect brain directly" (sic!).

Left hand or right hand?

But what does the science say? If you have read about phone radiation before, you may have seen the acronym SAR (Specific Absorption Rate) which gives you an idea of the radiation you get from a phone, though it doesn’t tell you anything too specific about a device. Still, we can use it to discuss your ear preference. Research papers about the effects of phone radiation show little difference in power absorbed by the user when the side they hold their phone on during a call is changed. This research has looked at different phones, antenna positions within the phone cases, tilt angles and operating frequencies (900 MHz or 1800 MHz) on both sides of the head,

It's not all about the head, though: what about the hand? Another paper adds the hand to the equation and shows its effects on both radiation absorbed by the user and the quality of the call. It is shown how the presence of the hand increases the power the user absorbs from the phone, but decreases the overall SAR as the hand takes a lot of the radiated power. However, the effect of the hand does not end there: it also heavily affects the quality of your reception when your hand covers the antenna.

The choice of the side to hold a phone on can be determined by investigating the design of the phone and the available networks in your area

You may remember the old days of pre-smartphones (the feature phones) at the turn of the century where the instruction manuals warned you not to cover the phone’s antenna (and you knew exactly where the antenna is, marked with a hole). Before that, you not only knew where the antenna was, but you probably had to pull it out manually.

Today we must search the internet to find out where our smartphone’s antennas are. It’s plural now: with the new technologies developing in each generation, the phones had to remain back-compatible and allow you to connect to old-tech base stations. This meant more hardware and more antennas integrated in the phone. You may remember GSM, the abbreviation synonymous with mobile phones at one point. That was the second generation technology and your phone can still use it today (the buzz on your hi-fi loudspeakers is a giveaway sign that someone’s using GSM).

From RTÉ Archives, RTÉ News report on the launch of the Eircell mobile telephone system in 1985 with prices starting from £1,400 plus VAT

This brings us to the question of what the choice of ear and hand does to the performance of these antennas. You don’t know where they are and the chances are that they are not placed on the mid-axis of the phone, so the side will matter. Every manufacturer makes their own choice on the design and placement of antennas, so the placement will vary depending on the phone, the frequency used and the network standard (generation).

A recent study from ComReg tested 71 phone models for the effects of human body on voice call quality. They used a phantom head with a hand holding the phone (these models match the properties of the human body). The phantom did not speak, so the quality of the call was measured with respect to total radiated power (TRP): the more power that gets through the head-hand blockade, the better the connection with the base station and the conversation quality.

From RTÉ Archives, Pamela Flood reports for Off the Rails in 2006 on how the mobile phone has become a fashion essential and status symbol

Take a look at the study yourself to find out which side, generation standard and frequency works best for your phone (table reading key: more is better, higher TRP is desired. GSM is the 2G standard, UMTS is the 3G standard). The tests were conducted on both sides of the head.

All phones show the difference in power between the two sides, but it is within reasonable bounds for most. In this sense, the most consistent are the old school feature phones, for example Nokia’s cult classic 3310 model with small difference in power based on the side. On the other hand (pun very much intended), iPhones seem to perform significantly worse in your left hand than in your right hand when running on GSM-900 and UMTS-900, but the opposite applies on GSM-1800 and UMTS-2100. Similar conclusions can be made about other smartphones (Samsung, HTC, or Motorola models). This means that for some smartphones, switching hands during a conversation could actually help.

It’s not just your preferred hand or the dubious information you find on social media. The choice of the side to hold a phone on (if you care about it at all) can be determined by investigating the design of the phone and the available networks in your area, a cute little engineering problem for the user. Check out the research and share it on your social media to outweigh the lazy memes and increase science-to-noise ratio.

Dr Harun Siljak is an EDGE MSCA Research Fellow at CONNECT at Trinity College Dublin


The views expressed here are those of the author and do not represent or reflect the views of RTÉ