It is important to train the client to do this without straining their voice. The third is called an “endurance” exercise, the client is instructed to hold a note as long as they can by controlling their exhale (this should be done with 3-4 comfortable pitches). While many transgender women wish to sing like cisgender women, it will require a lot of training for one to achieve a feminine-sounding voice. This is why most prepubescent males who begin hormone replacement therapy have a higher chance of retaining this quality. See castrato for more information. Non-surgical techniques undertaken by trans women and trans men as a part of gender transition to make the perceived gender of their voices match their gender. Voice feminization is the desired outcome of surgical techniques, speech therapy, self-help programs and a general litany of other techniques to acquire a female-sounding voice from a perceived male-sounding voice. Voice masculinization is the use of the same procedures and techniques to acquire a male-sounding voice. A voice prosthesis is an artificial device, usually made of silicone, that is used to help laryngectomized patients speak. A tube is inserted into the neck, below the vocal folds, allowing air to go through the tube instead of through the mouth and nose. Following a total laryngectomy, air will no longer pass through the vocal folds, significantly altering the person's ability to communicate orally. In some instances, the person may be able to block the tube with their fingers and breathe as they did before the surgery or attach a valve to their tube, which serves to allow air to enter while preventing food from passing into the windpipe. In others, this is not a viable option due to resistance, infection, and insufficient air. Voice therapy may then be turned to as a means for a person to regain the ability to communicate orally. Voice prostheses and ventilators may affect the volume of the speaker and the overall quality of the speaker's voice. With the help of voice therapy as well as possible adjustments to ventilator settings, the goal is to become accustomed to using the device functionally and to learn the techniques and skills needed to participate in daily communication. If the person is using a ventilator with their tube, there are long pauses between cycles of the ventilator. During these moments of silence, someone else may begin to speak, thus taking away the turn of the person with a ventilator. The person who has undergone a laryngectomy can use tools and techniques, such as those provided by a Speech-Language Pathologist (SLP) to self-advocate during conversations, in order to ensure that they are given the space that they need to participate in conversation.