Clive gave a great response (he always does!), but I believe in this context, the passage is saying that leaders need to be open to idea from many people, and they need to be open to these ideas whether they are expressed by a woman or man, a young person or an older person. They need to be open to them whether they are expressed as helpful ideas or as criticism. They need to be open to whatever is being said - the content, the facts, the main message.
That is, if someone complains about something, they need to realize there may be a real problem. Just because it was expressed as a complaint, it does not mean there is not a real issue.
That is, if the company is mostly middle-aged men and some newly hired young woman makes an observation, they need to consider it, even though it came in a different "voice" than they usually hear.