Grindcore vocals represent a prevalent style of deep, guttural singing and screaming found in extreme metal genres like Grindcore, Deathcore, Hardcore, and Death Metal. Originated and popularized by the British metal band, Napalm Death, the Grindcore vocal technique has been adopted across various forms of extreme metal. It involves manipulating the vocal cords while breathing to create a distinct guttural sound. This vocal technique requires careful shaping of the mouth to produce specific sounds and words, resulting in the characteristic low or high guttural vocals.
Steps

Stay Hydrated with Lukewarm Water Before and After Vocalization: Always hydrate with lukewarm water, avoiding alcoholic, acidic, or dairy beverages before or after performing scream vocals. These drinks can damage the protective layer of the throat and vocal cords. Lukewarm water and warm tea help to soothe and prepare the throat.

Practice Controlled Breathing Exercises: Begin by inhaling and exhaling slowly, gradually increasing the intensity and duration of breaths. Practice reciting the alphabet softly, gradually escalating to a loud yell. These exercises help to stretch and condition the vocal cords for screams, yells, and gutturals.

Developing Raspy Vocals: Inhale deeply to create a raspy sound, akin to simulating an asthma attack. Exhale deeply with a sigh to achieve a similar raspiness, as if reacting lazily to a chore. Repeat both exercises and determine which is easier for you. If inhaling is easier, focus on inhaled gutturals (Step 4). If exhaling is easier, focus on exhaled gutturals (Step 5). If both are feasible, choose the more comfortable option.

Inhaled Gutturals: Quietly practice inhaling until it feels natural. Begin by saying 'or' aloud and maintain the mouth position while inhaling. Keep practicing until you can articulate various words comfortably. Experiment with new words and sounds, progressing to the 'ee' sound.

Exhaled Gutturals: Exhale forcefully with an 'O' mouth shape to create a growling effect. Blow slightly while exhaling for a hollow sound. Practice until you can pronounce words like 'oh' loudly, then progress to other words. Attempt everyday conversation using growled vocals.

Accessing Low Voice: Open your mouth slightly wider and exert more force to reach your lowest chest voice. Gradually increase effort until breaking into your low voice becomes natural. This is where the guttural is produced.

Mastery of Low Voice: Practice until speaking in your low voice feels comfortable. Words spoken in this voice should sound like gurgles, indicating proper technique.

Practice the gutturals repeatedly until you're proficient in vocalizing with distortion. Obtain CDs of your preferred vocalists who utilize guttural techniques and endeavor to emulate their pitch using your own gutturals.
PointersRehearse gutturals from bands you admire
Opt for brief practice sessions to prevent vocal cord strain, which can impede sound production.
Always hydrate with room temperature or warm water, non-Pepsi carbonated drinks, or milk prior to guttural performances.
Cautionary NotesWhile not inherently wrong, encircling the microphone with your hands to produce gutturals is generally frowned upon by audiences across various extreme music genres, and you may face ridicule for it.
Not everyone comprehends the demands of a Grind vocalist, so be prepared for criticism and disparagement from death metal enthusiasts, purists, and those who fail to recognize the value of Grindcore.
If you experience discomfort in your voice, take a break from performing immediately!
Remember to keep your vocal cords lubricated with any of the mentioned fluids. Dry vocal cords can lead to vocal damage, hindering your ability to perform temporarily or causing permanent harm to your throat.