The 6th topic
Actually, how far can the voice travel?

This time, we will explain about transmission range. Please enjoy it.

In health checkup, we have hearing test. In the test, we concentrate on hearing to catch the faint sound. We say “Yes” when we catch the faint sound of “pi--, pi--, pi--”. The way to measure transmission range is same as hearing test. Transmission range is the max. distance we can hear the faint sound of “pi--”. According to this way of measurement, Logosease has 300m transmission range. Can we communicate if we are 300 meters away each other? No, we cannot. It is quite natural that we cannot understand the words spoken in very faint voice we barely hear.
Depending on the sea condition, actual transmission range may become short. In the very calm and clear sea, the sound “pi--” reaches 300m away, but such condition is quite rare. In the stormy sea, the sound reaches only 30m away.
Due to the reason above, we announce that practical transmission range of Logosease is between 50m to 100m in recreational diving. In the test we conducted, we could communicate well to the distance of 70m. When the distance becomes longer, the sound you can hear becomes smaller. At the distance of approx. 100m, we had difficulty understanding what the buddy spoke. This is just an example. It really depends on the sea condition.

After reading above, you may think “We can communicate underwater in the range of 50m”. It is both right and wrong because transmission range depends on speaking and hearing directions. The round, shiny, metallic component of Logosease is the antenna which transmits ultrasonic wave, which is equivalent to mouth and ears of human. The antenna transmits and receives ultrasound.
In case of human, since both mouth and ears face forward, we can converse most clearly in face-to-face position. On the other hand, we cannot converse well in back-to-back position. Feature of Logosease is completely same as this. When divers are in face-to-face position, conversation is the clearest, and in back-to-back, what said will be hard to hear

Please see the figure above. There is a diver speaking at the center. Suppose you are seeing the diver when you are hearing what he/she said, the blue area shows the area where you can communicate well. Divers can transmit the voice quite far away forward, but in backward, transmission range decreases to its 20 percent compared to the one in forward. The left side of the diver is “shadow zone”. It is the other side from where Logosease is set, and sound does not reach there well with the block of the body of the diver. If you are a bit away from the diver, the sound would reach you going around the diver, but if you are close to the diver, you can not hear in the shadow area.

Since Logosease has directionality, to make the conversation clear, you should speak seeing the buddy hearing you, and hear seeing the buddy speaking to you. If conversation does not go well, either speaking person should see the hearing person while speaking, or hearing person should see the speaking person while hearing. In this way, conversation will be much clear. Moreover, using this feature, you can get a hint to find where your speaking buddy is. When you hear the voice of your buddy, turn around there. You will notice the voice level differences facing different directions. In most cases, you will find the buddy where you hear the voice loudest and clearest. It will be quite effective to identify who it is in case of only seeing dim shape of a diver. However, situation will be different if there are any blocks as rocks between divers.
When you are trying to speak to your buddy whose location is not clear, try to speak 3 times to the direction where you think he/she might be, and wait for the reply. If no reply, turn 90 degrees and speak 3 times. Try this in all 4 directions. The buddy will hear you one of 4 directions. However, if there are any blocks as rocks between divers, your buddy may not hear you.

Let me summarize this topic.

  1. Practical max. communication range in the recreational diving with Logosease is 50m to 100m.
  2. It has directionality. Voices can be transmitted forward farthest, and in backward, only 20% compared to one in forward.
  3. There is shadow zone on the left side of the diver. Sound does not reach well
  4. When you converse, either you should see the buddy who hears, or vice versa.
  5. When you use directionality of the unit, you can get the tip in searching a speaker.
  6. If you can not see your buddy, speak to him/her in 4 directions.

Until now, we have announced communication distance of Logosease that its range is within visible range. The reason for this is that the communication distance differs largely in speaking and listening, and we expressed as “visible range” so that it is easy to understand.
However, we have gotten many inquiries from underwater workers, and we changed description in the specification.