"In The Haunted House" is the eighth episode of season one of the animated children's series The Magic School Bus. It originally aired on October 30th, 1994.
Carlos has invented a new instrument, but it sounds awful. The class is on their way to the sound museum for a performance when The Magic School Bus breaks down. They spot an old house, which turns out to be the museum. They enter to look for a phone, but the door locks behind them, forcing them to stay the night. While exploring the house, they discover what causes sounds to be heard.
In class, the students rehearse for the musical with each different student playing a different instrument. Ralphie is on the xylophone, Phoebe is on the saxophone, Arnold is on the sousaphone, Tim is on the violin, Keesha is on the clarinet, Liz is on the drums, Wanda is on the trombone, and Carlos has a special instrument he invented himself, with Dorothy Ann as the music conductor. When Carlos plays his instrument, it elicits dissonance and fails to complement the orchestra. Ms. Frizzle then comes around wearing a costume with various of instruments. She takes off the costume and the class tell her about Carlos' instrument, which is devoid of harmony, and the rehearsal at the sound museum is this afternoon.
Ms. Frizzle leads the class to The Magic School Bus and the class take a ride. Carlos decides to put a blue top hat on the instrument to make it sound better, which proves to be futile. When Carlos says that he need more time, Ms. Frizzle alters The Magic School Bus' speed and it eventually breaks down. Ms. Frizzle exits the bus and takes in temperature before she finally concludes that The Magic School Bus is overheated, telling the class they will be stuck in the woods for a while, which gives Carlos enough time to work on the sound of his instrument, only for Dorothy Ann to worry about missing the rehearsal.
When night falls, the students have to push the bus uphill while Ms. Frizzle hauls it. They stop when they hear a sound. Carlos had put an umbrella on his instrument to have a thunder sound to it, as well as a mane to sound like a lion's roar. Dorothy Ann rebuffs those decisions, telling him that the thunder sounds more like a drizzle and the mane sounds more like a kitten.
As the students continue to push The Magic School Bus, they hear another sound. They think that it was from Carlos' instrument. But Carlos denies this, and the student view a house. They walk to it and Carlos says that it's kind of "eary". When Ms. Frizzle rings the doorbell, which makes a peculiar sound, Arnold, Ralphie, and Tim decide to leave. But Carlos wants to know what made the sound. So the students reluctantly enter the house and the door makes a loud sound as it shuts.
Inside the house, the students search through the house for a phone. When Ralphie discovers that the doors are locked, Ms. Frizzle says "hello" in a loud voice. Her echo travels through the hallways and Ms. Frizzle says that it sound friendly enough. Dorothy Ann finds a phone book and the others hear the phone ringing. Ms. Frizzle picks a book off the shelf, which blows a foghorn when flipped open. Carlos then concludes that the books were making the sounds and Ralphie turns to leave, only to trip over a book. Ms. Frizzle then shows the class a picture of Professor Cornelia C. Contralto, eccentric collector of sounds, born in the year 1807 and disappeared in 1892. It is not known how she disappeared. Ms. Frizzle then tells the students that after her disappearance, the house turned into a sound museum, which is confirmed Dorothy Ann's prediction that the class missed the rehearsal. Ms. Frizzle also explains that Professor Contralto devoted her life towards sound and her whereabouts are obscure. Ralphie surmises that Professor Contralto is a ghost seeking for the perfect sound. Ms. Frizzle also tells the class that they would be spending the night, much to Arnold's fear. When Tim steps on a panel, the class comes across a rotating wall, which propels them to an adjacent bedroom replete with ample beds.
When the students go to bed, Carlos decides to put a blanket over his instrument to make it sound like a ghost. When Dorothy Ann once again rebuffs that tactic, Carlos asks for Professor Contralto's help, which elicits a tremendous lightning. Convinced that it's the call of Cornelia, Carlos leaves the room to find the sound and the students reluctantly follow along. The sound gets louder as they get closer to it. They hear a yodeling sound through a door, which Carlos enters, only to find a jungle inside. There is also pictures of the beach and city inside as the class enters and the yodeling continues. The students have a vociferous conversation, eliciting echoes. Just then, Ms. Frizzle arrives and is revealed to be the one yodeling. In the mountain paintings, she gives the students a ride up the chair lifts and they fall into a room of instruments. Ms. Frizzle elucidates that Professor Contralto built every room in the house to show different things about sound. Dorothy Ann comes across a harp and pulls the string, vibrating it. Carlos then concludes that the vibration of the string is what was making the sound. Tim and Phoebe try out the drum and Wanda tries out the gong, both of which makes the same vibrating sound. Carlos then figures that he needs vibration to make his instrument sound better. The sounds the students make causes the wall to crack open, revealing a different room. Carlos notices a pair of goggles on a statue and puts them on, which causes him to see the sounds. The other students put on goggles for themselves as well, and Ms. Frizzle informs them that high sounds elicit vibrations close to another, made by something vibrating quickly, and the low sounds elicit vibrations far apart from each other, made by something vibrating much slower. Ralphie compares the motion of the vibrations to ripples in a pond when something is thrown inside of it. Carlos then figures that his instrument can vibrate regardless of its appearance and runs inside the bedroom to grab it, only to find that it is now missing.
When the students search around the room, wind blows out the candles, dimming the bedroom, and Carlos hears the sound again. He searches through a closet and falls into a secret dungeon-like room. The students follow along and use their goggles to follow the mysterious sound. They soon learn that it's the sound waves that elicits echoes and find that the sound waves are coming from a mysterious door they come across. Carlos opens the door and finds a woman playing sounds with her organ. The woman introduces herself to the students as Professor Cornelia C. Contralto II, and that she is the great granddaughter of Professor Cornelia C. Contralto herself. She tells Carlos that she is helping him make his instrument sound better for the concert tomorrow. Carlos then learns that his instrument had too much stuff on it, which prevent any form of vibration, and that is what made it sound bad. So he eliminates any unwanted materials out of his instrument.
The next day, the class performs at the sound museum and when it comes Carlos' turn, his instrument elicits a unique, harmonic sound and ends with a thunder sound (which involves a shoe kicking a trash can lid). The audience applaud at the performance and Dorothy Ann tells Carlos that it was the perfect sound, and hugged him. Professor Contralto II also asks him if she could add this sound to her great grandmother's collection, which Carlos agrees since the professor helped him. Professor Contralto II and Ms. Frizzle, who is in her instrument costume, then make a performance of their own as the students watch in amusement.
- Professor Cornelia C. Contralto II was voiced by Broadway actress and singer Carol Channing.
- Everyone's parts in the concert:
- The TV tie-in book was called "In the Haunted Museum."
- In the producer segment, an invisible ghost speaks to the caller instead of one of the producers.
- The original rare version aired in 1994 had Ralphie comparing the motion of sound waves to ripples moving in water in a "report" segment. Before the segment, Ms. Frizzle said to him "An observation of a demonstration". Also, Keesha talked about how an echo is made. This rare version with the deleted scenes is also found on a Magic School Bus audio cassette called "Sounds".
- The musical piece the class was performing is "William Tell Overture - Finale".
- Clips are used for the grand finale of Kids for Character.
- This is the first time The Magic School Bus breaks down; the second time is in "Revving Up". And the first time it doesn't shapeshift. The 2nd time is in "Under Construction".