What is IEC 60601-1-8?

Standard IEC 60601-1-8 encompasses the use of audible and visual alarms in medical equipment. It is a subsection of parent standard IEC 60601, which covers all medical equipment requirements. The prefix “IEC” is an acronym for a European commission that sets standards for different applications and industries across Europe.

Figure 1: Standard IEC 60601-1-8 encompasses the use of audible and visual alarms in medical equipment. Source: Mallory Sonalert Products

Is IEC 60601-1-8 compliance required in the U.S.?

Although IEC 60601-1-8 is a European originated standard, the U.S. FDA requires compliance to it for medical equipment. In addition, Canada also recognizes this standard.

Are there different versions of IEC 60601-1-8, which one is active and for how long?

There are currently two active versions: IEC 60601-1-8 AMD1 and IEC 60601-1-8 AMD2:2020. The cut-off date for IEC 60601-1-8 AMD1 is December 17, 2023, per the supplemental information sheets from the FDA web-based directory of consensus standards. This means that after December 17, 2023, medical companies submitting equipment to the FDA must meet IEC 60601-1-8 AMD2:2020.

What are the requirements from IEC 60601-1-8 AMD1 for audible alarms?

There are two main sections in IEC 60601-1-1 AMD1 that dictate the specific requirements for audible alarms: Tables 3 and 4 and Appendix F.

Specific requirements in Tables 3 and 4 are:

· A sound frequency component must be between 150 Hz to 1,000 Hz, and it must be one of four frequency components with the largest sound level.

· There must be at least four frequency peaks between 150 Hz and 4,000 Hz.

· The sound level of the largest four frequency peaks between 150 Hz and 4,000 Hz should be within 15 dB of each other.

· Tables 3 and 4 also list the sound signal’s rise and fall times requirements, and it lists the specific pulse timings for the low, medium and high priority medical sounds.

Appendix F lists specific melody tones for medical applications, including: general, cardiac, artificial perfusion, ventilation, oxygen, temperature/energy delivery, drug or fluid delivery, and equipment or supply failure. As the name implies, the general melody can be used for any application. These melodies are like brief “tunes” being played on a piano, and each melody has the same rhythm, but different notes. The idea is that medical staff could eventually tie a melody with its associated medical application after hearing it enough times. Unfortunately, this did not work out well in actual medical environments (see next FAQ).

What changed from IEC 60601-1-8 AMD1 to AMD2:2020?

The one main change from IEC 60601-1-8 AMD1 to AMD2:2020 as it pertains to audible alarms is that Appendix F in AMD1 is replaced by Appendix G in AMD2:2020. Appendix G states that a medical company can use IEC freely supplied .WAV sound files for the different melody tones. So, each melody tone from AMD1 Appendix F has a corresponding .WAV sound file that replaces it. The reason for this change is that the Appendix F melody tones could not be distinguished from each other very well in actual medical situations.

What did not change from IEC 60601-1-8 AMD1 to AMD2:2020?

One thing that did not change, as it pertains to audible alarms, is that AMD1 Tables 3 and 4 were carried through to AMD2:2020. This means if you are using an audible alarm with a general tone under AMD1, this audible alarm will still meet IEC 60601-1-8 AMD2:2020.

Why will the .WAV sound files from AMD2:2020 work better than the AMD1 melody sounds?

The .WAV sounds are more distinct from each other than the AMD1 Appendix F melodies. Also, the .WAV sounds incorporate sound elements that are related to the medical application that it is assigned to. For example, the .WAV cardiac sound incorporates into it what could be described as a heartbeat.

Does IEC 60601-1-8 dictate the alarm’s sound level?

The short answer is no, and it is up to the medical equipment design team to determine the audible alarm sound level needed for any specific application. In practice, it is recommended that the alarm sound level should be at least 6 dB to 10 dB above the ambient background noise level.

There are a few requirements in IEC 60601-1-8 regarding relative sound level. Two of these are listed in Tables 3 and 4, which gives some guidance on the relative sound level of the different medical sound frequency components (see the fourth FAQ above). The other significant mention of sound level in the standard is that the low priority medical sound should not be louder than the medium priority sound, and the medium priority sound should not be louder than the high priority sound.

The standard does allow for all three medical priority sounds to be at the same sound level, which is the most practical implementation of this guidance. This is because if the medium priority sound level is 6 dB louder than the low priority sound, and the high priority sound is 6 dB louder than the medium, then the high priority sound will likely be too loud for the application, or alternatively, the low priority sound will be too soft to be heard. To hear a significant difference in sound levels, a 6 dB spread is needed. For a sound to be heard by the human ear as twice as loud, a 10 dB difference is needed.

Do all medical applications have to use the low, medium and high priority sounds?

It is up to the medical equipment designers to determine the status of the medical condition, how that relates to the patient, and how high of a priority it is to alert the medical staff. For example, if a patient is having a heart attack, a high priority general or cardiac melody sound is the obvious choice. It is possible the medical equipment/application may need to use one, two or all three medical priority tones depending on the status of the patient’s condition.

What about non-medical sounds?

IEC 60601-1-8 does state that non-medical sounds, such as a short beep whenever a key or button is pressed, should not be similar to the low, medium or high priority medical sounds. Other than that, it is up to the medical equipment designers to determine when non-medical sounds are needed and what kind of warning sound should be used including the sound level, sound frequency and sound type.

How can I produce the non-medical sounds?

If the alarm producing the low, medium or high priority medical sounds is also capable of producing non-medical sounds, then that would likely be the low-cost option since only one alarm component needs to be installed and controlled. However, a separate piezo buzzer can also be used for non-medical sounds, and while it would cost a little more to do this, it would keep the two sound control systems separate, which may be easier design-wise, and easier to document two separate sound systems for the IEC 60601-1-8 approval process.