Notes

Control: This refers to the refinement of the instrumental sound in a musically appropriate and consistent manner. Performers with good control over their instruments (or voices) will be able to produce accurately the exact sound they desire.
Breath support: This is the physical process of producing an instrumental sound using proper breathing technique. Breath support refers to breathing out air in a controlled fashion so that there is a smooth flow of air while playing a wind instrument. Singers also need to possess good breath support in order to articulate vocal sounds properly.
Projection: Projection is the strength, volume, and clarity of the tone of an instrument projected while performing. Breath technique is an important aspect of projection along with vocal chord and diaphragm strength for singing or playing wind instruments. Good projection is a sign of good technique.

Vibrato: Vibrato is when a tone fluctuates regularly between high and low pitch while playing the instrument. It gives the note a quavering quality. High-quality vibratos maintain the rate and depth of the fluctuation consistently.
Embouchure: Embouchure is the position of the facial muscles including the lip, jaw, and tongue in relation to the instrument and the performer’s physical characteristics. When done properly, it allows the musician to play the instrument to its best capacity, without damaging the player’s muscles.

Posture:Posture is the position of the body, arms, hands, and fingers in relation to the instrument and the performer’s physical characteristics. Posture can affect breathing and breath support, which in turn will affect performance. A sunken chest or a tense abdomen will not be conducive to efficient performance. Good posture helps commence phonation, improves blood circulation, and also improves the self-confidence of the musician and allows the musician to play the instrument (or sing) easily and effectively.


Intonation
This is the accuracy of pitches in relation to each other. Here, a musician tries to match other musicians’ pitches. The level of intonation of an ensemble depends on the listening skills of the players and the embouchure. Well-intonated instruments will sound harmonious when played together, while badly intonated instruments will sound out of place. The following criteria describe intonation:

Tuning: This is the ability of an instrument to match the pitch of a fixed standard. In order to ascertain well-intonated instruments, musicians tune their instruments to a set standard, called a tuning. An untuned instrument will not produce the desired sound even if the musician plays the piece with great accuracy. Tuning also helps define a standard that facilitates the communication of music between different performers and instruments. Listen to this recording of a tuned cello.

Tonality: This describes the ability of a performer to play a tuned instrument and maintain proper intonation. Set pitches denoted by notes divide the range of an instrument; proper tonality ensures that the same note has the same pitch throughout.
a cello player playing a cello


Technique
Technique judges the physical ability and mechanical dexterity required to produce notes correctly. Technique can pertain to either voice or instruments. This is the performer's ability to produce the right musical effect by properly controlling their instruments oFacility: This refers to the smoothness of the flow or movement of the hand while playing an instrument. Facility can also refer to nimbleness of the performer's hands or hand coordination. Musicians that use their hands (and on some occasions, feet) to play instruments must be quick. Fingers and joints need to move quickly and precisely in order to play the required notes.
Flexibility: This refers to the ease of maneuverability. Musicians must move their hands all over the instrument, for example the fretboard of a guitar, the keys of a piano, and so on. Good flexibility allows musicians to maneuver through the entire range of the instrument with ease.

Facility: This refers to the smoothness of the flow or movement of the hand while playing an instrument. Facility can also refer to nimbleness of the performer's hands or hand coordination. Musicians that use their hands (and on some occasions, feet) to play instruments must be quick. Fingers and joints need to move quickly and precisely in order to play the required notes.
Flexibility: This refers to the ease of maneuverability. Musicians must move their hands all over the instrument, for example the fretboard of a guitar, the keys of a piano, and so on. Good flexibility allows musicians to maneuver through the entire range of the instrument with ease.

Accuracy
This refers to the exact realization of notated music. When musicians perform a musical piece off a musical score, the term accuracy defines how close the performer gets to reproducing all of the notations as transcribed. The higher the accuracy, the closer the performer is to playing the piece exactly as transcribed in sheet form. The following terms define the accuracy of playing:

Articulation: This refers to a technique of transitioning or extending the continuity of notes or sounds. As with speech, performers also make use of articulation to produce different types of sounds even when playing (or singing) the same type of note. Articulations can be tenuto (held for a full length), staccato (sounded for a shortened duration), legato (smooth and connected), and so on. A performer should be able to understand articulation as transcribed in sheet music and perform the piece with accurate articulation.

Accuracy of notes: This refers to playing (or singing) the correct notes as written down in sheet music. The performer should be able to hit the notes accurately without any mistakes or unintentionally hitting the wrong notes.
Accuracy of rhythm: This refers to playing (or singing) the rhythm correctly. The performer needs to play (or sing) notes properly as transcribed in the sheet for the marked durations and with the correct articulation to produce the rhythm properly.

Steadiness of rhythm: This refers to maintaining the rhythm as transcribed. The performer needs to play (or sing) the individual notes properly with accurate articulation. The performer also needs to maintain proper tempo as mentioned in the sheet.
Pulse: This refers to the natural accents (strong and weak) implied by the meter of the musical piece. A highly accurate performer will be able to follow the pulse of accents correctly and play at the right pulse as transcribed.

Interpretation
When music is composed, it is often recorded as sheet music on paper. When a musician or singer performs a musical piece by another composer, the performer makes numerous decisions on how to perform the piece based on the sheet. The performer interprets his or her own version of the composer’s intent in the performance. Different performers may interpret the same composition differently, adding their own style and technique to the composition. When a performer interprets a composer's work, it can vary based on the following criteria:

Dynamics: This refers to the relative volume of a note or part of a musical piece. Using terms such as p (piano) and f (forte) for soft and loud, composers can assign volume levels to parts of a work relative to the overall volume. Because the overall volume is not set, the exact volume measure is up to the performer's interpretation.
a musician playing a cello


Style: This refers to the feel of the music, based on the musical intent consistent with either a historical era or a specific genre. The performer needs to have a clear understanding of the composer's musical style in order to interpret the work true to the composer's intent. However, this is not always true, because some performers may wish to interpret the work in a different style, for example a jazz interpretation of a Romantic Period musical piece.
Tempo: This refers to the speed of the composition. Composers usually record the tempo of the music at the top of the composition (unless there is a change in tempo). This uses a definite measure denoted in beats per minute (bpm). A performer should follow the prescribed tempo to produce the rhythm exactly as imagined by the composer.

Phrasing: This refers to the structuring of a musical idea by grouping consecutive notes in composition. A phrase is the smallest unit of a composition that is capable of conveying a musical thought. Phrasing is important while interpreting a composition because it marks a section that has to be played or sung in a single breath.
Expression: This refers to the performer’s ability to interpret the composition and communicate the composer’s emotions. Composers create musical works to elicit some feeling or emotion. The performer needs to understand this correctly and convey the emotion properly.
Artistry: This refers to the performer's musical and expressive involvement in the music. This defines the performer's ability to interpret and recreate the composition exactly as the composer visualized.

Using the aforementioned criteria, a listener can evaluate any musical performance, whether performed by a group of musicians, an orchestra, or even a solo performer. A good performance will score high on all the criteria. The performance criteria mentioned are interdependent, so if a performance lacks in a single criteria (for example, a badly intonated instrument) it will automatically result in a poor performance in the other criteria.

Music schools, such as the New York State School Music Association, use these criteria to grade performances. Based on this model of criteria, each group is graded and given a rating. A good all-around performance scores high in all criteria groups.

You can compare musical performances to some of the great musicians known for their technique or quality. For example, you can compare the breath support of a singer to Tony Bennett, who has excellent breath control over his entire vocal range. You can compare musicians with the greats for similarity in technique, style, and tone. For example, you can compare pianists’ technique based on Liszt even when considering their own original compositions.


Appropriate Concert Behavior
Audiences at concerts pay to watch and enjoy performances. To respect the rest of the audience as well as the performers, people must follow certain norms and etiquette while attending concerts. Some of them include the following:

Avoid talking. Talking also includes whispering or disciplining a child.
Do not open noisy candy wrappers during a performance.
Turn off electronic devices such as cell phones, tablets, and pagers.
Do not wave to the performers during the concert. You may be blocking the view of the rest of the audience.
Do not eat or drink during the concert. Eat or drink during the intermission.
Avoid flash photography during the performance. This causes distractions.

It is not acceptable to walk down the center of the aisle shooting with a video camera.
Do not walk out after a specific performer’s portion is over. Stay for the entire performance.
Applaud at the right times. This is particularly important in selections with multiple movements. You may take notice from seasoned concertgoers and take their lead about when to clap.
Do not leave during the music. Wait for a break to leave for the washroom.
Respect other people’s personal space when you are moving around in your seat or while walking around.
If you are late for the concert, do not try shoving other people to get to your place. Wait to be seated until the next break.
Dress appropriately.